Intermediate temperature molecular beam-epitaxy growth for design of large-area metal-semiconductor-metal photodetectors

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Abstract
Large-area metal-semiconductor-metal (MSM) photodetectors are fabricated on molecular beam epitaxy (MBE) grown GaAs material at growth temperatures ranging from 250 to 500 °C. It is shown that materials grown at intermediate temperatures are a suitable choice for large-area, high photocurrent detectors. Particularly, MSM devices made from material grown at around 350 °C have a dark current of the same magnitude as those grown at lower temperatures while having a substantially larger photocurrent. Higher low-field mobility at intermediate temperatures should give these devices speed advantage as well. A change of close to 4 orders of magnitude in dark current and more than 2 orders of magnitude in light response is observed for this temperature range.