A novel junction profile measurement in HgCdTe epilayer by laser beam induced current

2011 
A novel, sample junction profile measurement in HgCdTe epilayer is investigated. This measurement is used a scanning laser microscope to obtain the laser beam induced current (LBIC) signals of photosensitive pixel arrays on a long beveled HgCdTe epilayer, and the junction profile is extracted from the LBIC data. In this work, junctions are fabricated by B + implantation, and the beveled surface which is about 10mm long and several micrometers deep is formed by wet-etching way. Because of different epilayer thicknesses on the HgCdTe beveled surface, some n regions of pixels are totally removed at the deeper side, and the others have residual n regions at the shallower side. Therefore the very position where the LBIC signal begins to vanish would point out the boundary between junction region and non-junction region, and then the junction depth is extracted from the boundary data. The lateral sizes of junction at different depths are determined by the peak-to-peak space in LBIC signals. The junction profile of both Hg vacancies doped and Arsenic doped HgCdTe was measured in this work. The junction depth is about 1.29μm in Hg vacancy doped HgCdTe and a significant lateral expansion was observed at low temperature. The junction depth is about 5.48μm in arsenic doped HgCdTe. Moreover, the new technique is applicable to either HgCdTe or other materials.
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