Temperature dependence characteristics and noise characteristics of InGaAs/InAlAs X-ray APDs

In this paper, the temperature dependence characteristics and noise characteristics of InGaAs/InAlAs X-ray avalanche photodiodes (APDs) with different structures have been investigated. Firstly, according to the current-voltage curve under 50 keV hard X-ray radiation and activation energy at temperatures between 298 and 358
$\mathbf{K}$
., it is found that the thermal generation in the absorber layer (i.e., generation-recombination current) dominates the dark current. Secondly, there is a linear dependence of breakdown voltage with temperature and the temperature coefficient can be extracted for each device. The lowest temperature coefficient is 16.20 mV/K, which is conducive to operating in a complex environment. Ultimately, the noise of commercial InGaAs/InP APDs has been compared. Combining experimental and theoretical analysis, our results show that homemade devices have the advantage of low noise because the InAlAs multiplication layer with lower impact ionization coefficients
$(\boldsymbol{k})$
exhibits narrower gain distributions for X-ray APDs.