MOLECULAR-BEAM EPITAXY GROWTH AND INSITU ARSENIC DOPING OF P-ON-N HGCDTE HETEROJUNCTIONS

In this paper we present, results on the growth of in situ doped p-on-n heterojunctions on HgCdTe epilayers grown on (211) B GaAs substrates by molecular-beam epitaxy (MBE). Long wavelength infrared (LWIR) photodiodes made with these grown junctions are of high performance. The n-type MBE HgCdTe/GaAs alloy epilayer in these structures was grown at T(s) = 185-degrees-C and it was doped with indium (high 10(14) cm-3 range) atoms. This epilayer was directly followed by the growth, at T(s) = 165-degrees-C, of an arsenic-doped (10(17)-10(18) cm-3) HgTe/CdTe superlattice structure which was necessary to incorporate the arsenic atoms as acceptors. After the structure was grown, a Hg annealing step was needed to interdiffuse the superlattice and obtain the arsenic-doped p-type HgCdTe layer above the indium-doped layer. LWIR mesa diodes made with this material have 77 K R(O)A values of 5 X 10(3), 81, 8.5, and 1.1 OMEGA cm2 for cutoff wavelengths of 8.0, 10.2, 10.8, and 13.5-mu-m, respectively; the 77 K quantum efficiency values for these diodes were greater than 55%. These recent results represent a significant step toward the demonstration of MBE as a viable growth technique for the in situ fabrication of large area LWIR focal plane arrays.