Development and fabrication of extended short wavelength infrared HgCdTe sensors grown on CdTe/Si substrates by molecular beam epitaxy

• DOI: 10.1016/j.sse.2014.06.037
• Publication Date: 2014-08-28T23:46:06Z
• Authors: Sina Simingalam; Brenda L. VanMil; Yuanping Chen; Eric A. DeCuir; Greg P. Meissner; Priyalal Wijewarn...; Nibir K. Dhar; Mulpuri V. Rao
• Keywords: Cadmium telluride photovoltaics

Abstract The development and fabrication of extended short-wavelength infrared (SWIR) HgCdTe (MCT) sensors grown on CdTe/Si substrates is reported. The MCT epilayers were grown on CdTe/Si substrates by molecular beam epitaxy (MBE). The epilayers were evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray double crystal rocking curve (DCRC), Van der Pauw Hall measurements, dislocation defect–decoration etching and Nomarski microscopy. The FTIR analysis revealed a cutoff wavelength of 2.25 μm at 300 K which corresponds to a cadmium composition of 47%. As-grown epilayers have void defect densities less than 10 3 cm −2 and etch pit densities of ∼1 × 10 7 cm −2 . The Hall mobilities of annealed MCT samples are on the order of 1500 cm 2 /Vs and have carrier concentrations of ∼1 × 10 16 cm −3 at 300 K. Samples were doped in situ with indium (donor) and ion-implanted with arsenic (acceptor) to fabricate p–n diodes with sizes ranging from 15 μm to 250 μm diameter. We present the results and analysis of temperature dependent current–voltage ( I – V ) and quantum efficiency/responsivity measurements on the p–n diodes. In our analysis, we found that the I – V characteristics of small devices were dominated by shunt currents and quantum efficiency is limited by Shockley–Read–Hall (SRH) mechanisms.