Lifetime Testers

1. Theory

• Definition: Lifetime testers measure how long excess electron-hole pairs survive in a semiconductor by generating them with light and recording the excess conductance, either in steady state or during decay (PV-Manufacturing.org; SEMI MF1535).
• Effective lifetime: The measured value combines bulk recombination (Shockley-Read-Hall, radiative and Auger) and surface recombination (PV-Manufacturing.org; Martin et al.; SEMI MF1535).
• Injection dependence: Lifetime depends on the excess carrier density, so it must be quoted at a stated injection level (SEMI MF1535; CENIMAT).
• Solar-cell link: The excess density at one sun gives the implied open-circuit voltage, an upper limit on the cell voltage (CENIMAT).

2. Working Principle

• QSSPC: A slowly decaying flash, shorter than 100 $m/s$, keeps the wafer in quasi-steady state; the conductance and the light intensity are recorded together (PV-Manufacturing.org; Martin et al.).
• Transient: A short flash is followed by the free decay, for lifetimes much longer than the flash (CENIMAT; Martin et al.).
• Microwave PCD: A laser pulse excites a small spot and the microwave reflectance tracks the decay, enabling maps (SEMI MF1535; Karlstad).
• Surface passivation: Dielectric films or chemical passivation suppress surface recombination so the bulk lifetime can be seen (SEMI MF1535; Macdonald and Cuevas, whose oxidised rear has S below 10 $cm/s$).

3. Applications

• Wafer acceptance: Detection of metallic contamination in electronic-grade silicon (SEMI MF1535).
• Solar cells: Passivation quality, emitter saturation current and implied Voc during processing (CENIMAT; Janssen et al.).
• Process control: Lifetime maps after furnace steps reveal contamination patterns (Karlstad; SEMI MF1535).

Photoconductance Lifetime

Name	Formula	Related Formulae	Variables/Constants
Excess photoconductance	${\sigma }_L=q\left(\Delta n{\mu }_n+\Delta p{\mu }_p\right)W=q\Delta n\left({\mu }_n+{\mu }_p\right)W$	$\Delta n=\frac{{\sigma }_L}{q\left({\mu }_n+{\mu }_p\right)W}$	${\sigma }_L:excesssheetconductance$ $\begin{array}{r}\Delta n,\Delta p:excesselectronandhole\\ densities(equalunderillumination)\end{array}$ ${\mu }_n,{\mu }_p:mobilities$ $\begin{array}{r}W:waferthickness;PV-Manufacturing.org:\\ theseequations,lightpulsesshorterthan\\ 100m/s,QSSPCafterSintonandCuevas\\ (1996);CENIMAT:WCT-120sheet-resistance\\ range3to600\Omega /\mathrm{sq}(undoped)\end{array}$ $\begin{array}{r}(assumed:W=180\mu \mathrm{m},{\mu }_n+{\mu }_p=1400\\ \mathrm{c}{\mathrm{m}}^2/(\mathrm{V}\mathrm{s});computed:\Delta n=1\times 10^{15}\mathrm{c}{\mathrm{m}}^{-3}gives\\ {\sigma }_L=4.0\mathrm{mS})\end{array}$
Quasi-steady-state lifetime	${\tau }_{eff}=\frac{\Delta n_{av}qW}{J_{ph}}=\frac{{\sigma }_L}{J_{ph}\left({\mu }_n+{\mu }_p\right)}$	$G=\frac{J_{ph}}{qW}$	${\tau }_{eff}:effectivelifetime$ $\Delta n_{av}:averageexcessdensity$ $\begin{array}{r}{J}_{ph}:photogeneratedcurrentdensity(total\\ recombination)\end{array}$ $\begin{array}{r}G:averagegenerationrate;\\ PV-Manufacturing.org:theseequations;\\ Martinetal.:G_{av}=I_{ph}{f}_{opt}/w,writtenherewith\\ J_{ph}=q{I}_{ph}{f}_{opt}\end{array}$ $\begin{array}{r}(assumed:J_{ph}=38mA/c{\mathrm{m}}^{2}atonesun;\\ computed:G=1.32\times 10^{19}\mathrm{c}{\mathrm{m}}^{-3}{\mathrm{s}}^{-1},and\Delta n=\\ 1\times 10^{15}\mathrm{c}{\mathrm{m}}^{-3}means{\tau }_{eff}=76\mu \mathrm{s})\end{array}$
Transient and generalized lifetime	${\tau }_{eff}=-\frac{\Delta n}{d\Delta n/dt}(\text{transient})$	${\tau }_{eff}=\frac{\Delta n}{G\left(t\right)-d\Delta n/dt}(\text{generalized})$	$\begin{array}{r}G(t):time-dependentgenerationrate\\ duringtheflash;Martinetal.:\\ generalizedformafterNageletal.,PCD\\ formwithG=0;CENIMAT:WCT-120QSSPC,\\ transientandgeneralizedmodes,100\mathrm{ns}to\\ 10m/srange,injectioncalibratedfrom\\ 1\times 10^{13}to1\times 10^{16}\mathrm{c}{\mathrm{m}}^{-3},lightbias0to50\\ suns,40to210\mathrm{mm}samples,10to2000\mu \mathrm{m}\\ thickness\end{array}$ $\begin{array}{r}(computed:thegeneralizedformreducesto\\ theQSSonewhend\Delta n/dt\ll Gandtothe\\ transientonewhenG=0)\end{array}$

Recombination Components

Name	Formula	Related Formulae	Variables/Constants
Effective, bulk and surface lifetime	$\frac{1}{{\tau }_{eff}}=\frac{1}{{\tau }_b}+\frac{1}{{\tau }_s}$	${\tau }_s=\frac{W}{2S}(\text{from }1/{\tau }_{eff}=1/{\tau }_b+2S/W)$	${\tau }_b:bulklifetime$ ${\tau }_s:surfacelifetime$ $\begin{array}{r}S:surfacerecombinationvelocity(equal\\ onbothsides);Martinetal.:\\ 1/{\tau }_{eff}=1/{\tau }_b+2S/w,validwhentheeffective\\ diffusionlengthexceedsw;SEMIMF1535:\\ bulklifetimemeasuredonlywithout\\ surfacerecombinationandatlow\\ injection,surfacerecombinationvery\\ difficulttosuppresscompletely,1/eand\\ primary-modelifetimes\end{array}$ $\begin{array}{r}(assumed:W=180\mu \mathrm{m};computed:S=10cm/s\\ limits{\tau }_{eff}to0.9m/sandS=1000cm/sto\\ 9\mu \mathrm{s})\end{array}$
Recombination components	$\frac{1}{{\tau }_b}=\frac{1}{{\tau }_{SRH}}+\frac{1}{{\tau }_{rad}}+\frac{1}{{\tau }_{Auger}}$	${\tau }_{SRH}=\frac{{\tau }_{p0}\left(n_0+n_1+\Delta n\right)+{\tau }_{n0}\left(p_0+p_1+\Delta n\right)}{n_0+p_0+\Delta n}$	${\tau }_{SRH}:Shockley-Read-Halllifetime$ ${\tau }_{rad}:radiative$ ${\tau }_{Auger}:Auger$ ${\tau }_{n0},{\tau }_{p0}:capturetimeconstants$ $\begin{array}{r}{n}_1,p_1:trap-leveldensities;\\ PV-Manufacturing.org:U_{SRH},{\tau }_{rad}and{U}_{Aug}\\ forms,{\tau }_{SRH}herefrom\tau =\Delta n/U_{SRH}(computed);\\ Janssenetal.:{\tau }_{SRH}varieswithinjection\\ dependingonthecapturetimeconstants;\\ SEMIMF1535:metallicimpuritiesabove\\ about1\times 10^{10}atomspercubiccentimetre\\ reducelifetime,higherinjectionoften\\ usedforsignal-to-noise\end{array}$ $\begin{array}{r}(computed:inp-typewithadeeptrapat\\ lowinjection{\tau }_{SRH}\to {\tau }_{n0};athighinjectionit\\ tendsto{\tau }_{n0}+{\tau }_{p0})\end{array}$
Emitter saturation current (Kane-Swanson)	$\frac{1}{{\tau }_{eff}}-\frac{1}{{\tau }_{Auger}}=\frac{1}{{\tau }_{SRH}}+\frac{2J_0\left(N_A+\Delta n\right)}{q{n}_i^{2}W}$	$J_0=\frac{q{n}_i^{2}W}{2}\frac{d\left(1/{\tau }_{eff}-1/{\tau }_{Auger}\right)}{d\Delta n}$	$\begin{array}{r}{J}_0:emitterorsurfacesaturationcurrent\\ densityperside\end{array}$ $N_A:basedoping$ $\begin{array}{r}{n}_i:intrinsicdensity;Janssenetal.:J_0\\ fromtheslopeofcorrectedinverse\\ lifetimeagainst\Delta n,theKaneandSwanson\\ method;thefactor2(N_A+\Delta n)/(q{n}_i^{2}W)fortwo\\ identicalsides(myreading);QSSPCdata\\ athighinjectionused\end{array}$ $\begin{array}{r}(assumed:J_0=10fA/c{\mathrm{m}}^{2}perside,N_A=\\ 1.5\times 10^{16}\mathrm{c}{\mathrm{m}}^{-3},\Delta n=1\times 10^{15}\mathrm{c}{\mathrm{m}}^{-3},n_i=9.65\times 10^9\\ \mathrm{c}{\mathrm{m}}^{-3};computed:thetermis1190{\mathrm{s}}^{-1},\\ limiting{\tau }_{eff}to0.84m/s)\end{array}$

Implied Voltage and Mapping

Name	Formula	Related Formulae	Variables/Constants
Implied open-circuit voltage	$i{V}_{oc}=\frac{k_{B}T}{q}\ln \left[\frac{\Delta n\left(N_A+\Delta n\right)}{n_i^2}\right]$	$V_{oc}\le i{V}_{oc}$	$\begin{array}{r}i{V}_{oc}:impliedopen-circuitvoltagefromthe\\ excessdensityatonesun;\\ PV-Manufacturing.org(Suns-Voc):thisform\\ forap-typewafer;CENIMAT:calibrated\\ lifetimegivestheimpliedVoc,theupper\\ limitforVocandameasureofpassivation\\ quality;Suns-Voconcontactedjunctions\\ measurestheillumination-Voccurve\\ withoutseries-resistanceeffects,0.006\\ to6suns,forshuntandseries-resistance\\ diagnosis\end{array}$ $\begin{array}{r}(computed:\Delta n=1\times 10^{15}\mathrm{c}{\mathrm{m}}^{-3}on{N}_A=1.5\times 10^{16}\\ \mathrm{c}{\mathrm{m}}^{-3}givesi{V}_{oc}=0.669\mathrm{V}at300\mathrm{K}with{n}_i=\\ 9.65\times 10^9\mathrm{c}{\mathrm{m}}^{-3})\end{array}$
Microwave photoconductance decay	$\frac{\Delta R}{R}\propto \Delta \sigma (\text{small signal})$	$\Delta \sigma \left(t\right)\propto \exp \left(-\frac{t}{{\tau }_1}\right)(\text{primary mode})$	$\begin{array}{r}\Delta R/R:relativechangeofmicrowave\\ reflectance\end{array}$ $\Delta \sigma :excessconductivity$ $\begin{array}{r}{\tau }_1:primary-modelifetime;SEMIMF1535:\\ decayofconductivityafteralightpulse\\ monitoredbymicrowavereflectance,\\ noncontactandnondestructive,1/eand\\ primary-modelifetimes,conditionsagreed\\ betweensupplierandpurchaser;Karlstad:\\ SemilabWT-2000mapseffectivelifetime\\ withabout1\mathrm{mm}resolution,typically\\ microsecondstoafewmillisecondsfor\\ solar-gradesilicon;Martinetal.:\\ photoconductancemonitoredthroughchanges\\ inmicrowavereflectance;proportionality\\ forsmallsignals(myreading)\end{array}$ $\begin{array}{r}(computed:a156\mathrm{mm}squarewaferat1\mathrm{mm}\\ pitchisabout24300points)\end{array}$

Important Questions

Ques: How does a photoconductance lifetime tester work?

By measuring the extra conductance that light-generated carriers add to a wafer. Equal densities of excess electrons and holes raise the sheet conductance by $q\Delta n({\mu }_n+{\mu }_p)W$ (PV-Manufacturing.org), so the measured conductance gives the excess density. For a 180 $\mu \mathrm{m}$ wafer with a summed mobility of 1400 $\mathrm{c}{\mathrm{m}}^2/(\mathrm{V}\mathrm{s})$, $1\times 10^{15}$ $\mathrm{c}{\mathrm{m}}^{-3}$ adds 4.0 $\mathrm{mS}$ (assumed values; computed). In the quasi-steady-state method a flash shorter than 100 $m/s$ decays slowly enough that generation and recombination balance, and a calibrated cell measures the light (Martin et al.), giving ${\tau }_{eff}=\Delta nqW/J_{ph}$. At one sun, with an assumed 38 $mA/c{\mathrm{m}}^2$, $1\times 10^{15}$ $\mathrm{c}{\mathrm{m}}^{-3}$ means 76 $\mu \mathrm{s}$ (computed). The method was introduced by Sinton and Cuevas in 1996. Reference: PV-Manufacturing.org, ‘Photoconductance decay’ metrology page (author not stated) (fetch-tool summary); I. Martin, A. Alcaniz, A. Jimenez, G. Lopez, C. del Canizo and A. Datas, ‘Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates’, arXiv:2006.13969 (IEEE J. Photovolt. 2020): tau_eff = dn_av/(G_av - d dn_av/dt) after Nagel et al., QSS requires a flash decay much slower than the lifetime, PCD with G = 0, G_av = I_ph f_opt/w, 1/tau_eff = 1/tau_b + 2S/w, W-PCD via microwave reflectance (fetch-tool summary).

Ques: When should the QSS, transient or generalized mode be used?

It depends on the lifetime compared with the flash. The quasi-steady-state analysis assumes the flash changes slowly compared with the lifetime, so Martin et al. require a flash decay much slower than the effective lifetime. The transient analysis, $\tau =-\Delta n/(d\Delta n/dt)$, uses only the decay after the flash, reached for lifetimes much longer than the flash (Martin et al.). The generalized form $\Delta n/(G-d\Delta n/dt)$ covers both, reducing to the QSS result when the decay term is small and to the transient one when generation stops (Martin et al., after Nagel et al.; computed limits). The Sinton WCT-120 at CENIMAT offers all three, with a range of 100 $\mathrm{ns}$ to 10 $m/s$, calibrated injection from $1\times 10^{13}$ to $1\times 10^{16}$ $\mathrm{c}{\mathrm{m}}^{-3}$, light bias up to 50 suns, and samples 40 to 210 $\mathrm{mm}$ across and 10 to 2000 $\mu \mathrm{m}$ thick. Reference: I. Martin, A. Alcaniz, A. Jimenez, G. Lopez, C. del Canizo and A. Datas, ‘Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates’, arXiv:2006.13969 (IEEE J. Photovolt. 2020): tau_eff = dn_av/(G_av - d dn_av/dt) after Nagel et al., QSS requires a flash decay much slower than the lifetime, PCD with G = 0, G_av = I_ph f_opt/w, 1/tau_eff = 1/tau_b + 2S/w, W-PCD via microwave reflectance (fetch-tool summary); CENIMAT (NOVA University Lisbon), ‘Sinton WCT and Suns-Voc lifetime measurements’ facility page (fetch-tool summary).

Ques: Why does the measured lifetime differ from the bulk lifetime?

Because carriers also recombine at the surfaces. The effective lifetime combines both, $1/{\tau }_{eff}=1/{\tau }_b+1/{\tau }_s$, and for low surface recombination velocity S, ${\tau }_s=W/(2S)$, from Martin et al.’s $1/{\tau }_{eff}=1/{\tau }_b+2S/W$. A 180 $\mu \mathrm{m}$ wafer with S = 10 $cm/s$ is limited to 0.9 $m/s$, and with 1000 $cm/s$ to 9 $\mu \mathrm{s}$ (computed), whatever the bulk quality. SEMI MF1535 states that bulk lifetime is obtained only without surface recombination and at low injection, and that complete suppression is very difficult, so its method is designed to work without perfect passivation. Macdonald and Cuevas, for example, measure cells with an oxidised rear whose recombination velocity is below 10 $cm/s$. Reference: I. Martin, A. Alcaniz, A. Jimenez, G. Lopez, C. del Canizo and A. Datas, ‘Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates’, arXiv:2006.13969 (IEEE J. Photovolt. 2020): tau_eff = dn_av/(G_av - d dn_av/dt) after Nagel et al., QSS requires a flash decay much slower than the lifetime, PCD with G = 0, G_av = I_ph f_opt/w, 1/tau_eff = 1/tau_b + 2S/w, W-PCD via microwave reflectance (fetch-tool summary); SEMI MF1535, ‘Test Method for Carrier Recombination Lifetime in Electronic-Grade Silicon Wafers by Non-Contact Measurement of Photoconductivity Decay by Microwave Reflectance’, SEMI store abstract (fetch-tool summary); D. Macdonald and A. Cuevas, ‘The Use of Injection-Level Dependent Lifetime Measurements for Determining Solar Cell Parameters’, ANU: trapping centres make the lifetime increase dramatically with decreasing injection, onset about 5e13 cm-3 in their mc-Si (fetch-tool summary).

Ques: Why must lifetime be quoted at a stated injection level?

Because each recombination mechanism depends differently on the excess density. From PV-Manufacturing.org’s rate, the Shockley-Read-Hall lifetime of a deep level in p-type material changes from ${\tau }_{n0}$ at low injection to ${\tau }_{n0}+{\tau }_{p0}$ at high injection, and its Auger rate, $C_n{n}^{2}p+C_{p}n{p}^2$, makes the Auger lifetime fall as $1/\Delta n^2$ at high injection (computed limits); Janssen et al. note the SRH dependence on the capture time constants. A single wafer can therefore show lifetimes differing several times between $1\times 10^{14}$ and $1\times 10^{16}$ $\mathrm{c}{\mathrm{m}}^{-3}$. SEMI MF1535 notes that low injection avoids this influence but that higher injection is often used for signal-to-noise, so conditions must be agreed between supplier and purchaser. The WCT-120 is calibrated from $1\times 10^{13}$ to $1\times 10^{16}$ $\mathrm{c}{\mathrm{m}}^{-3}$ (CENIMAT). Reference: PV-Manufacturing.org, ‘Recombination processes’: U_SRH = (pn - ni^2)/[tau_p0(n + n1) + tau_n0(p + p1)], tau_rad = 1/[B(n0 + p0 + dn)], U_Aug = Cn n^2 p + Cp n p^2 (fetch-tool summary); G. J. M. Janssen, Y. Wu, K. C. J. J. Tool, I. G. Romijn and A. Fell, ‘Extraction of recombination properties from lifetime data’, Energy Procedia 92, 88-95, 2016: J0 from the slope of corrected inverse lifetime against excess density, the slope method of Kane and Swanson; tau_SRH varies with injection depending on the capture time constants (fetch-tool summary); SEMI MF1535, ‘Test Method for Carrier Recombination Lifetime in Electronic-Grade Silicon Wafers by Non-Contact Measurement of Photoconductivity Decay by Microwave Reflectance’, SEMI store abstract (fetch-tool summary); CENIMAT (NOVA University Lisbon), ‘Sinton WCT and Suns-Voc lifetime measurements’ facility page (fetch-tool summary).

Ques: What are implied Voc and Suns-Voc?

Two ways to predict a solar cell’s voltage before it is finished. The excess density at one sun fixes the separation of the quasi-Fermi levels, so the implied voltage is $(k_{B}T/q)\ln [\Delta n(N_A+\Delta n)/n_i^2]$ for a p-type wafer (PV-Manufacturing.org): $1\times 10^{15}$ $\mathrm{c}{\mathrm{m}}^{-3}$ on $1.5\times 10^{16}$ $\mathrm{c}{\mathrm{m}}^{-3}$ doping gives 0.669 $\mathrm{V}$ at 300 $\mathrm{K}$ (computed). CENIMAT describes it as the upper limit for Voc and a measure of passivation quality, available from calibrated lifetime data before metallization. Suns-Voc needs a contacted junction and records open-circuit voltage against illumination from 0.006 to 6 suns; since no current flows, series resistance does not affect it, so comparing it with the final I-V curve reveals series-resistance losses, and its low-light part reveals shunts. Reference: PV-Manufacturing.org, ‘Suns-Voc’: iVoc = (k_{B}T/q) ln[dn(0)(N_A + dn(0))/ni^2] for a p-type wafer (fetch-tool summary); CENIMAT (NOVA University Lisbon), ‘Sinton WCT and Suns-Voc lifetime measurements’ facility page (fetch-tool summary).

Ques: How does microwave PCD map lifetime?

By exciting a small spot with a laser pulse and watching the microwave reflectance decay. Excess carriers raise the conductivity, and Martin et al. note that in microwave PCD the photoconductance is monitored through changes in the microwave reflectance, so the reflectance transient tracks the carrier decay. SEMI MF1535 standardizes this for electronic-grade silicon, reporting the 1/e lifetime and the primary-mode lifetime, and notes that metallic impurities above about $1\times 10^{10}$ atoms per cubic centimetre already reduce lifetime. Because it is noncontact and nondestructive, wafers can continue processing if kept clean. Karlstad’s Semilab WT-2000 maps whole wafers at about 1 $\mathrm{mm}$ resolution, a 156 $\mathrm{mm}$ wafer being about 24300 points (computed), with typical solar-grade lifetimes of microseconds to a few milliseconds. Reference: I. Martin, A. Alcaniz, A. Jimenez, G. Lopez, C. del Canizo and A. Datas, ‘Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates’, arXiv:2006.13969 (IEEE J. Photovolt. 2020): tau_eff = dn_av/(G_av - d dn_av/dt) after Nagel et al., QSS requires a flash decay much slower than the lifetime, PCD with G = 0, G_av = I_ph f_opt/w, 1/tau_eff = 1/tau_b + 2S/w, W-PCD via microwave reflectance (fetch-tool summary); SEMI MF1535, ‘Test Method for Carrier Recombination Lifetime in Electronic-Grade Silicon Wafers by Non-Contact Measurement of Photoconductivity Decay by Microwave Reflectance’, SEMI store abstract (fetch-tool summary); Karlstad University, Materials Physics, ‘Lifetime Mapping’ characterization tools page (fetch-tool summary).

Ques: How is the emitter saturation current extracted, and what artefacts occur?

From the high-injection slope of inverse lifetime. After subtracting Auger recombination, $1/{\tau }_{eff}$ rises linearly with $\Delta n$ the slope method of Kane and Swanson (Janssen et al.); for two identical surfaces the slope is $2J_0/(q{n}_i^{2}W)$ (my reading). An assumed 10 $fA/c{\mathrm{m}}^2$ per side on a 180 $\mu \mathrm{m}$, $1.5\times 10^{16}$ $\mathrm{c}{\mathrm{m}}^{-3}$ wafer adds 1190 ${\mathrm{s}}^{-1}$ at $1\times 10^{15}$ $\mathrm{c}{\mathrm{m}}^{-3}$, limiting the lifetime to 0.84 $m/s$ (computed), so good emitters must reach the few-femtoamp range. Results depend on the intrinsic density and Auger model used. At low injection, trapping centres make the apparent lifetime increase dramatically as injection falls, with an onset near $5\times 10^{13}$ $\mathrm{c}{\mathrm{m}}^{-3}$ in Macdonald and Cuevas’s multicrystalline cells, so low-injection data should be treated with caution. Reference: G. J. M. Janssen, Y. Wu, K. C. J. J. Tool, I. G. Romijn and A. Fell, ‘Extraction of recombination properties from lifetime data’, Energy Procedia 92, 88-95, 2016: J0 from the slope of corrected inverse lifetime against excess density, the slope method of Kane and Swanson; tau_SRH varies with injection depending on the capture time constants (fetch-tool summary); D. Macdonald and A. Cuevas, ‘The Use of Injection-Level Dependent Lifetime Measurements for Determining Solar Cell Parameters’, ANU: trapping centres make the lifetime increase dramatically with decreasing injection, onset about 5e13 cm-3 in their mc-Si (fetch-tool summary).

References

1. PV-Manufacturing.org, “Photoconductance decay,” metrology page (author not stated). Available: https://pv-manufacturing.org/metrology/photoconductance-decay/
2. I. Martin, A. Alcaniz, A. Jimenez, G. Lopez, C. del Canizo and A. Datas, “Application of quasi-steady state photoconductance technique to lifetime measurements on c-Ge substrates,” IEEE J. Photovolt., 2020; arXiv:2006.13969. Available: https://arxiv.org/abs/2006.13969
3. PV-Manufacturing.org, “Recombination processes.” Available: https://pv-manufacturing.org/metrology/recombination-processes/
4. PV-Manufacturing.org, “Suns-Voc.” Available: https://pv-manufacturing.org/metrology/suns-voc/
5. G. J. M. Janssen, Y. Wu, K. C. J. J. Tool, I. G. Romijn and A. Fell, “Extraction of recombination properties from lifetime data,” Energy Procedia, vol. 92, pp. 88-95, 2016. Available: https://publications.tno.nl/publication/34633792/3u7RT9/w16023.pdf
6. D. Macdonald and A. Cuevas, “The use of injection-level dependent lifetime measurements for determining solar cell parameters,” Australian National University. Available: https://openresearch-repository.anu.edu.au/bitstreams/73876ddc-2394-4b8f-813b-35ea541d9542/download
7. CENIMAT, NOVA University Lisbon, “Sinton WCT and Suns-Voc lifetime measurements,” laboratory facility page. Available: https://www.cenimat.fct.unl.pt/lab-facilities/nanophotonics-and-energy-lab/sinton-wct-and-suns-voc-lifetime-measurements
8. SEMI, “SEMI MF1535: Test Method for Carrier Recombination Lifetime in Electronic-Grade Silicon Wafers by Non-Contact Measurement of Photoconductivity Decay by Microwave Reflectance,” standard abstract, SEMI store. Available: https://store-us.semi.org/products/mf153500-semi-mf1535-test-method-for-carrier-recombination-lifetime-in-electronic-grade-silicon-wafers-by-noncontact-measurement-of-photoconductivity-decay-by-microwave-reflectance
9. Karlstad University, Materials Physics, “Lifetime Mapping,” characterization and preparation tools page. Available: https://www.kau.se/fysik/forskning/materialfysik/kiselsolcellsforskning/characterization-and-preparation-tools-0

Related pages in this vault: Deep-Level Transient Spectroscopy (DLTS), Corona-Kelvin Metrology, Four-Point Probe, FTIR Spectrometer, EBIC and EBAC, Photoluminescence Spectrometer, Mercury Probe, Solar Cell Loss Mechanisms and Characterization, Generation-Recombination Models, Residual Gas Analyzer (RGA), Furnace Anneal System.