Minority carrier mobility measurement in HgCdTe with light-modulated Hall effect

Abstract

The light modulated Hall measurement system was set up in order to measure the minority carrier mobility of the p-type HgCdTe material. Minority carrier mobility is one of the main parameters for HgCdTe infrared photodetectors, because it determines the diffusion length of minority carriers, which plays a big role in the performance of optoelectronic devices. Therefore, it is important to get the minority carrier mobility in HgCdTe, so as to evaluate the material property before fabrication of photodetectors. By adding a modulated laser to the Hall system, the modulated Hall voltage was measured on p-type Hg1-xCdxTe(x=0.233) sample over a range of 0-1.8T in the magnetic field at temperature of 75K. The modulated signal is generated by the movement of excess photocarriers in the magnetic field, so it has a relationship with the magnetic field, the photogenerated carrier concentration and the electron and hole mobilities. Since the majority concentration and mobility can be derived from the Hall effect, the minority mobility and the photogenerated carrier concentration were obtained from fitting the light-modulated Hall voltage uVH as a function of the magnetic field B. As compared to the references, the minority mobility we have obtained is reasonable, so the light-modulated Hall effect is an effective way to obtain the minority carrier mobility.