Method, Computer Program, and System for Determining Respective Transport Properties of Majority as Well as Minority Charge Carriers in a Sample

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This patent describes a method, computer program, and system that accurately determine the transport properties (such as mobility, density, lifetime, diffusion length) of both majority and minority charge carriers (e.g., electrons and holes) in semiconductor samples. By performing multiple Hall effect measurements on a sample under varying illumination intensities, the technique enables independent and reliable extraction of properties for both types of charge carriers. It also provides correction algorithms to handle issues like parasitic conductivity and low signal-to-noise Hall effect data. The system can be applied to a range of semiconductors, including challenging materials such as perovskites, and is suitable for steady-state analysis (i.e., under conditions similar to actual device operation).

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• Characterizing semiconductor materials for solar cells to optimize their efficiency and predict device performance before fabrication.
• Analyzing and improving transistors and photodetectors where understanding transport properties of both electrons and holes is crucial.
• Research and development of new or advanced semiconductor materials, such as perovskites, where minority carrier properties are difficult to measure by traditional means.
• Diagnosing degradation, defects, or doping in semiconductor devices by revealing detailed carrier transport properties.
• Evaluating interface layers and transport layers in multilayer electronic or optoelectronic devices (e.g., in LEDs or p-i-n junctions).
• Educational and laboratory use to teach or demonstrate fundamental semiconductor physics, specifically carrier transport phenomena.

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• Provides accurate, independent measurement of both majority and minority carrier properties, not available from standard Hall or transient techniques.
• Enables analysis under steady-state (“real-world operating”) conditions rather than just transient or non-operational states.
• Corrects for practical measurement issues such as parasitic conductivities and signal-to-noise limitations, yielding robust data even for low-mobility or highly doped samples.
• Reduces the need for fabricating full device prototypes by predicting key parameters (like open circuit voltage and ideality factor) directly from material measurements.
• Facilitates development and optimization of semiconductor devices by giving deeper insight into how both carrier populations behave under different illumination intensities and device-relevant conditions.
• Applicable across a wide range of semiconductor types, including those with similar or dissimilar electron/hole mobilities (e.g., silicon, perovskites, organics).

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Patent Abstract

Method for determining respective transport properties of majority as well as minority charge carriers in a sample (107). The method allows to determine the charge carrier density of the majority charge carriers and the charge carrier density of the minority charge carriers. A plurality of Hall measurements are performed on the sample, wherein during each Hall measurement trial, the sample is exposed to an illumination intensity I, and a Hall coefficient and a conductivity are acquired. In a first Hall measurement the sample is exposed to a first illumination intensity I1, in the range of zero to 0.02 suns, and a first Hall coefficient RH (I1) and a first conductivity σ(I1) are acquired, wherein from the first Hall coefficient and the first conductivity, a carrier mobility µ1 is determined. In a second measurement the sample is exposed to a second illumination intensity I2 and a second Hall coefficient RH (I2) and a second conductivity σ(I2) are acquired, wherein from the second Hall coefficient and the second conductivity, a second carrier mobility µ2 is determined, wherein the second illumination intensity I2 is so high that a charge carrier density of electrons and a charge carrier density of holes in the sample (107) are identical, that the second Hall coefficient asymptotically approaches zero and that a second Hall mobility obtained from the product of the second Hall coefficient and the second conductivity asymptotically approaches a constant value. A third carrier mobility µ3 is determined from the first and the second carrier mobility, wherein the first carrier mobility µ1 is assigned to a mobility of the majority charge carriers, µ2 is assigned to the absolute value of the difference between hole and electron mobility, and the third carrier mobility µ3 is assigned to a mobility of the minority charge carriers in the sample.