26 October 1998 Metal organic vapor phase epitaxy of P-on-n HgCdTe/GaAs heterojunction
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Abstract
We report in-situ growth of MWIR P-on-n HgCdTe on GaAs by Metal Organic Vapor Phase Epitaxy. HgCdTe epi layers were grown by interdiffused multilayer process (IMP). Tris- dimethylarminoarsenic (DMAAs) was used as a precursor for arsenic doping (p-type layer) and isoprophyliodide (IPI) was used for iodine doping (n-type layer). Standard bubbler configuration was used for both precursors. Doping concentration could be controlled accurately in the range of 2 X 1015 to 7 X 1016 cm-3. After growth, HgCdTe layers were annealed in Hg-atmosphere at 415 degrees Celsius and 260 degrees Celsius consecutively. This Hg- annealing is for activating dopants and then reducing Hg- vacancy concentration. The layers doped with iodine in low 1015 cm-3 concentration showed higher Hall mobility than undoped layers. The Hall mobility of iodine doped layers decreased with increasing doping concentration. Secondary ion mass spectroscopy (SIMS) analyses for the iodine-doped layer showed sharp decrease of iodine concentration after IPI precursor being turned off, indicating negligible memory effect and very slow diffusion of iodine during growth and Hg-annealing. SIMS analyses for the arsenic doped layer showed that arsenic diffused by about 1 micrometer during growth and Hg-annealing. These results show that IPI and DMAAs could be used as stable precursors for in-situ growth of HgCdTe heterojunction. A P-on-n structure was grown. The P-layer has x composition of 0.32 and acceptor concentration of 6 X 1016 cm-3. The n-layer has x composition of 0.30 and donor concentration of 2 X 1015 cm-3. SIMS depth profile for the structure shows well-defined regions of doping concentration and alloy composition. After Hg-annealed, P-on-n structures were fabricated into MESA structure diodes. Electron beam evaporated CdZnTe was used as a passivation layer. This MWIR diode had RoA value of about 3 X 104 (Omega) .cm2.
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Jong-Hyeong Song, Jin-Sang Kim, Kwan-Uk Jung, Sang-Hee Suh, Sun-Ung Kim, Mann-Jang Park, "Metal organic vapor phase epitaxy of P-on-n HgCdTe/GaAs heterojunction", Proc. SPIE 3436, Infrared Technology and Applications XXIV, (26 October 1998); doi: 10.1117/12.328041; https://doi.org/10.1117/12.328041
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