Metalorganic chemical vapor deposition of HgCdTe p/n junctions using arsenic and iodine doping

We report new results on metalorganic chemical vapor deposition (MOCVD)in situ growth of long wavelength infrared (LWIR) P-on-n and medium wavelength infrared (MWIR) n-on-P HgCdTe heterojunction photodiodes using the interdiffused multilayer process (IMP). The n-type regions are doped with iodine using the precursor ethyl iodide (El). I-doped HgCdTe using El has mobilities higher than that obtained on undoped background annealed films and are comparable to LPE grown In-doped HgCdTe. The p-type layers are doped with arsenic from either tertiarybutylarsine (TBAs) or a new precursor,tris-dimethylaminoarsenic (DMAAs). The substrates used in this work are lattice matched CdZnTe oriented (211)B or (100)4°→«110». Junction quality was assessed by fabricating and characterizing backside-illuminated arrays of variable-area circular mesa photodiodes. This paper presents four new results. First, carrier lifetimes measured at 80K on arsenic doped single HgCdTe layers are generally longer for films doped from the new precursor DMAAs than from TBAs. Second, we present data on the first P-on-n HgCdTe photodiodes grownin situ with DMAAs which have R0A products limited by g-r current at 80K for λco = 7–12 μm, comparable to the best R0A products we have achieved with TBAs. Third, we report the first experimental data on a new HgCdTe device architecture, the n-on-P heterojunction, with a wide gap p-type layer which allows radiation incident through the substrate to be absorbed in a narrower gap n-type layer, thereby eliminating interface recombination effects. With the n-on-P architecture, MWIR photodiodes were obtained reproducibly with classical spectral response shapes, high quantum efficiencies (70-75%) and R0A products above 2 x 105 ohm-cm2 for λco = 5.0 μm at 80K. Fourth, we report 40K data for LWIR P-on-n HgCdTe heterojunction photodiodes (using TBAs), with R0A values of 2 x 104 ohm-cm2 for λco = 11.7 μm and 5 x 105 ohm-cm2 for λco- 9.4 μm. These are the highest R0A values reported to date for LWIR P-on-n heterojunctions grownin situ by MOCVD.

[1]  Michael Schenk,et al.  New defect etchants for CdTe and Hg1-xCdxTe , 1990 .

[2]  F. C. Case,et al.  Donor doping in metalorganic chemical vapor deposition of HgCdTe using ethyl iodide , 1994 .

[3]  R. Korenstein,et al.  Indium doping of HgCdTe grown by metalorganic chemical vapor deposition-direct alloy growth using triisopropylindium and diisopropyltellurium triisopropylindium adduct , 1993 .

[4]  I. Gale,et al.  Doping studies in MOVPE-grown CdxHg1-xTe , 1993 .

[5]  K. Maruyama,et al.  Iodine doping in mercury cadmium telluride (Hg1−xCdxTe) grown by direct alloy growth using metalorganic chemical vapor deposition , 1993 .

[6]  F. C. Case,et al.  Independently accessed back-to-back HgCdTe photodiodes: A new dual-band infrared detector , 1995 .

[7]  A. J. Brouns,et al.  Non-contact lifetime screening technique for HgCdTe using transient millimetre-wave reflectance , 1993 .

[8]  J. Bajaj,et al.  A new N-type doping precursor for MOCVD-IMP growth of detector quality MCT , 1993 .

[9]  D. Rosenfeld,et al.  Quantum efficiency and spectral response of compositionally graded HgCdTe P‐n heterojunction photodiodes , 1994 .

[10]  P. W. Norton,et al.  The impact of characterization techniques on HgCdTe infrared detector technology , 1993 .

[11]  P. Wisk,et al.  Growth of GaAs and AlGaAs by metalorganic molecular beam epitaxy using tris-dimethylaminoarsenic , 1992 .

[12]  K. Jensen,et al.  Chemical/surface mechanistic considerations in the design of novel precursors for metalorganic molecular beam epitaxy , 1994 .

[13]  A. Syllaios,et al.  Minority carrier lifetime in mercury cadmium telluride , 1993 .

[14]  C. Viswanathan,et al.  Novel very sensitive analytical technique for compositional analysis of Hg1−xCdxTe epilayers , 1992 .

[15]  R. Evershed,et al.  Mat Res Soc Symp Proc , 1995 .

[16]  T. Schimert,et al.  Metalorganic chemical vapor deposition of HgCdTe for photodiode applications , 1995 .