To improve the performance of photodiodes based on narrow-bandgap InAs/GaSb type-II strained layer superlattices (T2SLs), knowledge of the vertical minority carrier transport is necessary. For this purpose, the key parameters influencing vertical minority-carrier electron transport in an nBp MWIR detector were studied: diffusion length, lifetime, mobility. The detectors were designed with p-type, 10/10 ML, InAs/GaSb T2SL absorbers, targeting a 50% cut-off wavelength of 5.0 µm at 80 K. The nBp structure is attractive because the junction field predominately drops across a relatively wide-gap InAs/AlSb SL barrier, which reduces the expected generation-recombination dark current. Measurements of the electron beam-induced current (EBIC), combined with minority carrier lifetime results from microwave reflectance measurements, enabled the determination of the minority carrier diffusion length (Le) and mobility in the growth direction as a function of temperature. The Le was extracted at each temperature by fitting the EBIC data to analytical expressions for carrier collection efficiency. The EBIC measurements were also repeated at different electron-beam energies to vary the distribution of minority carriers near the surface to gauge the surface recombination velocity. Microwave reflectance allowed for accurate measurement of the minority carrier lifetime over a large dynamic range of excess carrier concentrations, enabling a separation of recombination mechanisms. The lifetime and extracted diffusion length data were then used to estimate the diffusion coefficient and mobility versus temperature by applying the Einstein diffusion relationship.
Z. Taghipour, E. H. Steenbergen, S. I. Maximenko, C. P. Morath, V. M. Cowan, S. Mathews, E. H. Aifer, G. Balakrishnan, and S. Krishna, "Vertical transport study of InAs/GaSb type-II superlattice nBp MWIR detectors using electron beam-induced current measurement," Proc. SPIE 10624, Infrared Technology and Applications XLIV, 106240N (Presented at SPIE Defense + Security: April 17, 2018; Published: 23 May 2018); https://doi.org/10.1117/12.2309658.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the proceedings. They include the speaker's narration with video of the slides and animations. Most include full-text papers. Interactive, searchable transcripts and closed captioning are now available for 2018 presentations, with transcripts for prior recordings added daily.
Search our growing collection of more than 16,000 conference presentations, including many plenaries and keynotes.