Annealing effect on the P-type carrier concentration in low-temperature processed arsenic-doped HgCdTe |
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Authors: | S H Shin J M Arias M Zandian J G Pasko L O Bubulac R E De Wames |
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Affiliation: | (1) Rockwell International Science Center, 91360 Thousand Oaks, CA |
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Abstract: | We report the results of annealing effects on the As-doped alloy HgCdTe grown by molecular beam epitaxy (MBE), arsenic (As)
diffusion in HgCdTe from Hg-rich solutions at low temperatures, and As ion implantation at room temperature. Hall-effect measurements,
secondary ion mass spectrometry and p-on-n test photodiodes were used to characterize the As activation. High As-doping levels
(1017−1019 cm−3) could be obtained using either MBE growth, As diffusion or As ion-implantation. Annealed below 400°C, As doping in HgCdTe
shows n-type characteristics, but above 410°C demonstrates that all methods of As doping exhibit p-type characteristics independent
of As incorporation techniques. For example, for samples annealed at 436°C (PHg≈2 atm), in addition to p-type activation, we observe a significant improvement of p/n junction characteristics independent
of the As source; i.e. As doping either in situ, by diffusion, or ion implantation. A study of this As activation of As-doped
MBE HgCdTe as a function of anneal temperature reveals a striking similarity to results observed for As diffusion into HgCdTe
and implanted As activation as a function of temperature. The observed dependence of As activation on partial pressure of
Hg at various temperatures in the range of 250 to 450°C suggests that As acts as an acceptor at high Hg pressure (>1 atm)
and as a donor at low Hg pressure (<1 atm) even under Hg-rich conditions. |
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Keywords: | As activation As diffusion MBE HgCdTe p-on-n photodiodes |
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