Valence band engineering of GaAsBi for low noise avalanche photodiodes

Abstract Avalanche Photodiodes (APDs) are key semiconductor components that amplify weak optical signals via the impact ionization process, but this process’ stochastic nature introduces ‘excess’ noise, limiting useful signal to noise ratio (or sensitivity) is practically achievable. The APD material’s electron and hole coefficients ( α β respectively) critical parameters in regard, with very disparate values of necessary minimize excess noise. Here, analysis thirteen complementary p-i-n/n-i-p diodes shows alloying GaAs ≤ 5.1 % Bi dramatically reduces while leaving virtually unchanged—enabling a 2 100-fold enhancement / extending wavelength beyond 1.1 µm. Such dramatic change only unseen any other dilute alloy attributed Bi-induced increase spin-orbit splitting energy ∆so ). Valence band engineering way offers an attractive route enable low APDs be developed.