The American Sinton WCT-120 minority carrier lifetime tester adopts the quasi-stable state photoconductivity (QSSPC) measurement method and analysis technology. It can sensitively reflect the heavy metal pollution, trap effect, surface recombination effect and other defects of single and multi-crystalline silicon wafers. WCT is a widely used detection tool in the research and development and production of ultra-high-efficiency solar cells (HIT, MWT, EWT, PREL, etc.) with an efficiency greater than 20%. This QSSPC method of measuring minority carrier lifetime can obtain an opening voltage curve similar to the illumination IV curve at any stage in the middle of battery production, and can be combined with the final IV curve to perform data monitoring and parameter optimization on the battery production process.
Sinton Instruments Minority Carrier Lifetime Tester Silicon Wafer Minority Carrier Lifetime Test System WCT-120
Shanghai Shunmiao Optoelectronics General Agent Supply American sinton WCT-120 Suns-Voc minority carrier lifetime tester
Silicon wafer minority carrier lifetime test system
American Sinton WCT-120 The minority carrier lifetime test instrument uses unique measurement and analysis techniques, including similar steady-state Photoconductance (QSSPC) Measurement method: It can sensitively reflect the defects of single crystal heavy metal pollution, trap effect, surface compound effect, etc. WCT A highly regarded research and process tool. QSSPC Lifetime measurements also produce an implicit open circuit voltage ( For lighting ) The curve, and the last IV The curves are comparable at each stage of a solar cell process.
The American Sinton WCT-120 minority carrier lifetime tester uses unique measurement and analysis technology, including the quasi-stable state photoconductivity (QSSPC) measurement method. It can sensitively reflect the heavy metal pollution, trap effect, surface recombination effect and other defects of single and multi-crystalline silicon wafers. WCT is a widely used essential detection tool in the research and development and production of ultra-high efficiency solar cells (HIT, MWT, EWT, PREL, etc.) with a efficiency greater than 20%. This QSSPC method of measuring minority carrier lifetime can obtain an open circuit voltage curve similar to the illumination IV curve at any stage in the middle of battery production, and can be combined with the final IV curve to monitor the data and optimize the parameters of the battery production process. Main applications: Distributed monitoring and optimization of manufacturing processes
Other applications:
Testing the performance of raw silicon wafers
Heavy metal contamination status of silicon wafers during the test process
Evaluate the quality of surface passivation and emitter diffusion doping
The obtained IV-like opening pressure curve is used to evaluate the production process caused by the production process. Leakage .
Key Features:
With just a tap, key performance tests of silicon wafers can be performed, including surface resistance, minority carrier lifetime, trap density, emitter saturation current density and implicit voltage.
Minority Carrier Lifetime Tester Silicon Wafer Minority Carrier Lifetime Test System WCT-120
Frequently Asked Questions:
Sinton WCT-120 What is the difference with WT-2000 in measuring minority carrier lifetime?
WCT uses the Quasi-Steady-State Photoconductance (QSSPC) quasi-steady-state photoconductivity decay method, while WT2000 uses the microwave photoconductivity decay method.
What is the principle of measuring minority carrier lifetime using the WCT-120 quasi-steady-state photoconductivity method?
Comparison between Quasi-steady-state Photoconductivity Decay (QSSPC) and Microwave Photoconductivity Decay (MWPCD)?
An important advantage of the QSSPC method over other lifetime testing methods is that it can make absolute measurements of excess carriers within a wide range of light intensity changes. At the same time, it can be combined with the SRH model to derive various recombination lifetimes, such as the minority carrier recombination lifetime caused by defect recombination centers in the body, the surface recombination velocity, and other relationships with carrier concentration.
The signal tested by the MWPCD method is a differential signal. The QSSPC method can test the true value of the minority carrier lifetime. In the case of bias light, MWPCD can be combined with theoretical calculations to derive the curve of minority carrier lifetime changing with excess carriers, while QSSPC can directly measure the excess carrier concentration, so the relationship curve between minority carrier lifetime and excess carrier concentration can be directly obtained, and the dark saturation current density of the PN junction can be obtained; because the pulsed laser spot used in MWPCD can be several to a dozen or even smaller in size, during the irradiation process, only the area within this size range will be excited to produce photogenerated carriers, that is, the result obtained is the difference lifetime value of the local area, which is not representative for samples with uneven lifetime distribution.
What are the performance parameters of minority carrier lifetime tester?
Measuring sample specifications: Standard diameter: 40–210 mm (or smaller);
Silicon wafer thickness range: 10–2000 μm;
Ambient temperature: 20°C–25°C;
Power requirements: Tester: 40W, Computer controller: 200W, Light source: 60W;
Universal power supply voltage: 100–240 VAC 50/60 Hz;
Who has successfully used the minority carrier lifetime tester? Silicon material production companies and semiconductor photovoltaic crystal pulling companies in Jiangsu, Shanghai, Beijing, Zhejiang, Xi'an, Sichuan, Hebei, Henan and other places, etc.
Zhejiang University, Sun Yat-sen University, Zhejiang Normal University, Comtec Solar, CSG Solar, Rongma New Energy, Shandong Runfeng Electric Power, Ningbo Jinle Solar, Ningbo Fuxing Solar, JA Solar, Hareon Solar, Changzhou Bitai, LDK, Suzhou Canadian Solar, Xi'an Longji, etc.
Please contact our technical staff for other information
Minority carriers life time:
(1) Basic concepts:
The carrier lifetime refers to the lifetime of non-equilibrium carriers. Non-equilibrium carriers are generally non-equilibrium minority carriers (because only minority carriers can be injected into the semiconductor and accumulated, and even if the majority carriers are injected, they will disappear quickly through the Coulomb effect), so the non-equilibrium carrier lifetime refers to the non-equilibrium minority carrier lifetime, that is, the minority carrier lifetime. For example, for n-type semiconductors, the non-equilibrium carrier lifetime refers to the lifetime of non-equilibrium holes.
For n-type semiconductors, the lifetime τ of the non-equilibrium minority carriers, the holes, is also the average survival time of the holes. 1/τ is the recombination probability of the holes per unit time. Δp/τ is called the recombination rate of non-equilibrium holes (that is, the number of electron-hole pairs that net recombine and disappear per unit time and per unit volume in the n-type semiconductor). The rate of change of the concentration of non-equilibrium carrier holes with time is dΔp/dt = -Δp/τp. If τp is independent of Δp, then Δp has an exponential decay law: Δp = (Δp) exp(-t/τp). Experiments show that under small injection conditions (Δp< of non-equilibrium carriers. It should be noted that only when the injection is small is the non-equilibrium carrier lifetime a constant, and the net recombination rate can be expressed as -Δp/τp; and under small injection, the lifetime of the stable state is equal to the lifetime of the transient state.
(2) Factors that determine life expectancy:
The factors that affect the lifetime of minority carriers in different semiconductors are mainly the recombination mechanism of carriers (direct recombination, indirect recombination, surface recombination, Auger recombination, etc.) and related issues. For semiconductors with indirect transitions such as Si and Ge, because the bottom of the conduction band and the top of the valence band are not at the same point in the Brillouin zone, the direct recombination of conduction band electrons and valence band holes is difficult (it requires the help of phonons, etc. to achieve - because the momentum conservation of carrier recombination must be satisfied), then the main factor that determines the lifetime of minority carriers is the indirect recombination process through the recombination center. Therefore, the recombination centers (types and quantities) caused by harmful impurities and defects in semiconductors have a great impact on the minority carrier lifetimes of these semiconductors. Therefore, in order to increase the minority carrier lifetime, harmful impurities and defects should be removed; on the contrary, if the minority carrier lifetime is to be shortened, some impurities or defects that can produce recombination centers can be added (such as doping Au, Pt, or bombardment with high-energy particle beams, etc.). For direct transition semiconductors such as GaAs, since the bottom of the conduction band and the top of the valence band are at the same point in the Brillouin zone, the main factor determining the minority carrier lifetime is the direct recombination process between the conduction band electrons and the valence band holes. Therefore, the minority carrier lifetime of such semiconductors is generally short. Of course, harmful impurities and defects will further promote recombination and shorten the lifetime.
(3) Impact of minority carrier lifetime on semiconductor devices:
For bipolar semiconductor devices that rely mainly on minority carrier transport (mainly diffusion) to work, minority carrier lifetime is an important parameter that directly affects device performance. At this time, a commonly used related parameter is the minority carrier diffusion length L (equal to the square root of the product of the diffusion coefficient and the lifetime), which represents the average distance that minority carriers can travel while diffusing and recombining. The longer the minority carrier lifetime, the greater the diffusion length.
For BJT, in order to minimize the recombination of minority carriers in the base region (to obtain a large current amplification factor), the base width must be shortened to below the diffusion length of minority carriers. Therefore, the lifetime of minority carriers in the base region should be as long as possible.
The minority carrier concentration is mainly determined by intrinsic excitation, so it is greatly affected by temperature.
Introduction:
Minority carrier lifetime is an important parameter of semiconductor materials and devices. It directly reflects the quality of materials and device characteristics. Accurately obtaining this parameter is of great significance for semiconductor device manufacturing.
Minority carriers, or minority charge carriers, are a concept in semiconductor physics. They are relative to majority carriers.
There are two types of carriers in semiconductor materials: electrons and holes. If a certain type of carrier is in the minority in a semiconductor material and plays a minor role in conduction, it is called a minority carrier. For example, in an N-type semiconductor, holes are minority carriers and electrons are majority carriers; in a P-type semiconductor, holes are majority carriers and electrons are minority carriers.
Formation of majority and minority carriers: Atoms of pentavalent elements have five valence electrons. When they replace tetravalent silicon atoms in the crystal lattice, four valence electrons in each pentavalent element atom are combined with the surrounding four silicon atoms in the form of covalent bonds, while the remaining one is not bound by the covalent bonds. The thermal energy it obtains at room temperature is enough for it to break free from the attraction of the nucleus and become a free electron. Since this electron is not a valence electron in a covalent bond, no holes are generated at the same time. For each pentavalent element atom, although it releases a free electron and becomes a positive ion with an electron charge, it is bound in the crystal lattice and cannot conduct electricity like a carrier. In this way, compared with the intrinsic excitation concentration, the concentration of free electrons in N-type semiconductors is greatly increased, while the chance of holes to recombine with free electrons increases, and their concentration is smaller instead.
Minority carrier lifetime is an important parameter of semiconductor materials and devices. It directly reflects the quality of materials and device characteristics. Accurately obtaining this parameter is of great significance for semiconductor device manufacturing.
Minority carriers are atoms formed by electrons being detached from them, and majority carriers are atoms formed by electrons being added to them.
The life time of minority carriers is the time from the formation of minority carriers to the combination of minority carriers and majority carriers.
American Sinton WCT-120 Suns-Voc minority carrier lifetime tester
There are many companies that have purchased the American Sinton minority carrier lifetime tester. The most recent purchasers are:
Sinton WCT-120 minority carrier lifetime tester from the United States Zhejiang University, Sun Yat-sen University, Zhejiang Normal University, Comtec Solar, CSG Solar, Rongma New Energy, Shandong Runfeng Electric Power, Ningbo Jinle Solar, Ningbo Fuxing Solar, JA Solar, Hareon Solar, Changzhou BiTai, Suzhou Canadian Solar, Talesun Power, Institute of Electrical Engineering of the Chinese Academy of Sciences, Jifu New Energy, Jingyao Technology, etc.
The users of American Sinton BCT400 minority carrier lifetime tester include GCL Group, Comtec Solar, Xi'an Longi, etc.
Keywords: Sinton Instruments minority carrier lifetime tester silicon wafer minority carrier lifetime test system wct-120
American Sinton WCT-120 Suns-Voc minority carrier lifetime tester
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