Abstract
Since avalanche gain and breakdown voltage in most semiconductor materials change with temperature, instruments utilizing Avalanche Photodiodes (APDs) for their avalanche gains need to incorporate either temperature stabilization or voltage adjustment in the APD operation circuits. In this work we evaluated the temperature and temporal stability of avalanche gain in Al0.85Ga0.15As0.56Sb0.44, a wide bandgap semiconductor lattice-matched to InP substrates. We investigated the temperature and temporal stability of the gain and breakdown voltage at temperatures of 24 °C (room temperature) to 80 °C. The breakdown voltage varies linearly with temperature with a temperature coefficient of 1.60 mV/K. The avalanche gain reduces from 10 to 8.5, a reduction of 15%, when the temperature increases from 24 to 80°C. The temporal stability of gain was recorded when the APD was biased to achieve an avalanche gain of 10. Fluctuations are within ± 0.7% at 24°C, increasing to ± 1.33% at 80°C. The temperature and temporal stability of avalanche gain indicates the potential of using Al0.85Ga0.15As0.56Sb0.44 APDs grown on InP substrates to achieve high tolerance to temperature fluctuation.
Highlights
Avalanche Photodiodes (APDs) are routinely used in optical detection systems, transforming weak optical signals into large photocurrents such that the signals are significantly larger than noise originating from electronics
In this work we evaluated the temperature and temporal stability of avalanche gain in Al0.85Ga0.15As0.56Sb0.44, a wide bandgap semiconductor lattice-matched to InP substrates
We investigated the temperature and temporal stability of the gain and breakdown voltage at temperatures of 24 °C to 80 °C
Summary
Avalanche Photodiodes (APDs) are routinely used in optical detection systems, transforming weak optical signals into large photocurrents such that the signals are significantly larger than noise originating from electronics. Based on data obtained at 77 to 297 K, Al1-xGaxAs0.56Sb0.44 APDs with ~100 nm thick avalanche layers exhibit small Cbd values of 0.86-1.08 mV/K, without signs of significant band-to-band tunnelling current [7] These APDs produce very low excess noise characteristics, with effective ionization coefficient ratios keff of 0.05-0.1 [8,9]. The Al1-xGaxAs0.56Sb0.44 APDs reported in [8,9,10] are superior to and distinct from earlier Al1-xGaxAs1-ySby APDs (x > 0.7 and y > 0.89), which are lattice-matched to GaSb substrates The latter have narrower bandgaps (0.7-1.2 eV) [10] and much thicker avalanche layers (several microns) [11], which gave higher excess noise keff of 0.2 [12] and Cbd ~30 mV/K in a 700 nm avalanche region [13]. Our study covers temporal stability of avalanche gain, with comparison to commercial Si APDs
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