Native Oxide of HgCdTe as a Passivation Layer

The effect of HgCdTe oxide on the electro- physical properties of the HgCdTe/Al2O3 interface has been investigated. The HgCdTe oxide was formed by pretreatment after wet etching in Br/HBr. Five samples with different surface treatments of HgCdTe after wetting chemical etching in Br/HBr were produced. The treatments were focused on changing the thickness of the HgCdTe native oxide. It was found for all samples that the difference between the flat band position voltages for the forward and reverse sweep increased when the voltage range was increased. The sample oxidized for a day in H2O2 vapor had the smallest difference between the positions of the flat bands. This indicates the smallest number of slow states in the intermediate layer on the HgCdTe/Al2O3 interface. In all samples, a flat band voltage had a shift. It indicated the presence of fixed built-in charge in the dielectric and/or intermediate layer. The HgCdTe series resistance was observed to affect the result when the measuring frequency was increased. The lowest value of the surface states density in the sample pretreated with TMA vapor without oxidation phase before Al2O3 growth was observed.