Performance characteristics of high-purity mid-wave and long-wave infrared type-Ⅱ InAs/GaSb superlattice infrared photodiodes

摘要

The authors report on recent advances in the development of mid-, long-, and very long-wavelength infrared (MWIR, LWIR, and VLWIR) type-Ⅱ InAs/GaSb superlattice infrared photodiodes. The residual carrier background of binary type-Ⅱ InAs/GaSb superlattice photodiodes of cut-off wavelengths around 5 μm has been studied in the temperature range between 10 and 200 K. A four-point, capacitance-voltage technique on mid-wavelength and long-wavelength type-Ⅱ InAs/GaSb superlattice infrared photodiodes reveal residual background concentrations around 5 x 10~(14) cm~(-3). Additionally, recent progress towards LWIR photodiodes for focal plane array imaging applications is presented. Single element detectors with a cut-off wavelength, λ_(c,50%), of 10.2 μm demonstrated detectivities of approximately 1 x 10~(11) cmHz~(1/2)W~(-1) and quantum efficiencies of 32% at the peak responsivity wavelength of around 7.9 μm. Furthermore, high-performance VLWIR single element photodiodes are discussed. The silicon dioxide passivation of VLWIR photodiodes is also presented, which resulted in an approximately 5 times increase of the sidewall resistivity. The latest developments in this material system lend further support for its use as a high-performance alternative for infrared optical systems compared to the current state-of-the-art imaging systems, especially those approaching the long-wavelength and very-long-wavelength infrared.