Near single-crystal electrical properties of polycrystalline HgI/sub 2/ produced by physical vapor deposition

Abstract

Polycrystalline films of HgI/sub 2/ prepared by physical vapor deposition (PVD) were found to have electrical charge transport properties similar to those of single crystals. Transient charge transport (TCT) measurements were used to evaluate the electrical conduction properties of the samples. The mobility /spl mu/, trapping time /spl tau/, and surface recombination velocity s of electrons or holes were determined by analyses of transient voltages developed across the sample in response to a drift of the corresponding charge carriers created by alpha particle absorption near one of the electrodes. Typical electron and hole mobilities were /spl mu//sub n/=88 cm/sup 2//V/spl middot/s and /spl mu//sub p/=4.1 cm/sup 2//V/spl middot/s, respectively; trapping times were /spl tau//sub n/>16 /spl mu/s and /spl tau//sub p/<3.5 /spl mu/s, and surface recombination velocities s/sub n//spl cong/1.4/spl times/10/sup 5/ cm/s and s/sub p//spl cong/3.7/spl times/10/sup 3/ cm/s. All parameters depend to a large extent on the material deposition technology. The effect of carriers being first generated in near-surface traps and then gradually released is observed.