Experimental Investigation of of the use of Elemental Transmutation for efficient p -type doping in HgCdTe and HgCdTeSe Contract Officer: Dr. W. Clark, Army Research Office. PI’s: T.D. Golding and C.L. Littler, University of North Texas. In collaboration with.
Experimental Investigation of of the use of Elemental Transmutation for efficient p-type doping in
HgCdTe and HgCdTeSe
Contract Officer: Dr. W. Clark, Army Research Office
PI’s: T.D. Golding and C.L. Littler, University of North Texas
In collaboration with
Dr. J.H. Dinan, US Army CECOM NVESD, Fort Belvoir
J.A. Dura, R.M. Lindstrom, NIST, Gaithersburg, MD
H.F. Schaake , DRS Infrared Technologies, Dallas, TX
Contract Period 8/15/01 – 8/14/04
Rational Transmutation for efficient
l Control of p-type doping processes in HgCdTe is a prerequisite to fabricate high performance infrared detector devices.
l Group I elements such as Li, Cu, Ag, and Au are readily incorporated into metallic sites giving p-type activity, their high diffusion coefficients restrict their use in advanced devices.
l Group V element As is preferred as a p-dopant because it has a low diffusivity.
l However, As is amphoteric within the HgCdTe lattice, occupying both metal and nonmetal sites, giving donor and acceptor characteristics respectively.
l Requires complex deposition and annealing schemes to give p-type behavior.
Rational (cont.) Transmutation for efficient
l Based on the fact that Se can be readily incorporated into group VI sites and that 75Se naturally decays into 75As.
l Method (I): Transmutation Doping (TD)
Progress to date Transmutation for efficient
Effects of neutron irradiation on transport properties
Magneto-conductivity tensor analysis of Hall anomalous transport effects (two-electron model)
Se incorporation in LPE HgCdTe
Transport and Magneto-Optics
“Nominally undoped HgCdTe epilayers will be supplied for this program by the US Army Night Vision Laboratories, and DRS Infrared…”
40 samples of LPE HgCdTe supplied to UNT by DRS: 10 samples of MBE HgCdTe supplied to UNT by NVEOL
”The control samples will be fully characterized at UNT by temperature dependent magnetotransport and magneto-optics to determine carrier levels, mobilties, compensation and defect levels…”
5 of control samples characterized by temperature-dependent magnetotransport. Concentrations, mobilities, and transport mechanisms determined for these samples.
“The HgCdTe alloys will be irradiated in a thermal neutron flux using the reactor facilities at the National Institute for Standards and Technology…”
5 of samples irradiated and characterized by temperature-dependent magnetotransport. Effects of irradiation on the properties of HgCdTe determined.
“The test samples will be characterized by SIMS to determine dopant (Se and As) profiles…”
2 samples implanted with As and Se (2 x 1014 cm-3)
Samples currently at DRS Infrared for activation anneal
Experimental Results this program by the US Army Night Vision Laboratories, and DRS Infrared…”n1 = 1.47 x 1014 cm-3
1 = 7.52 x 104 cm2/V.s
n2 = 1.85 x 1014 cm-3
2 = 2.67 x 104 cm2/V.s
Two Carrier Fit