ACHIEVEMENT OF LOW P-TYPE CARRIER-CONCENTRATION FOR MOCVD GROWTH HGCDTE WITHOUT AN ANNEALING PROCESS

The electrical characteristics of as-grown epitaxial HgCdTe layers gro wn by metalorganic chemical vapor deposition were investigated. We pro pose a new cap layer in order to obtain as-grown HgCdTe layers with lo w p-type carrier concentration. The new cap layer called the ''double- cap layer'' consists of a graded Cd content Hg1-xCdxTe layer with x = 0.2-0.7 and a CdTe cap layer which was continuously grown at low tempe rature on the graded HgCdTe layer. The carrier concentration of HgCdTe layers with the new cap layer was about 3 x 10(16) cm(-3). The p-type carrier concentration has been reduced further to 2x10(15) cm(-3) (fo r x = 0.22) by lowering the growth temperature and increasing the part ial pressure of Hg. This carrier concentration is lower than the estim ated Hg vacancy concentration from considerations of the thermal equil ibrium conditions. (C) 1998 Elsevier Science B.V. All rights reserved.