9 files

Valence Band Engineering of GaAsBi for Low Noise Avalanche Photodiodes

posted on 08.08.2021, 09:36 authored by Yuchen Liu, Xin Yi, Nicholas BaileyNicholas Bailey, Zhize Zhou, Thomas Rockett, Leh Lim, Chee TanChee Tan, Robert RichardsRobert Richards, John DavidJohn David

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 the useful signal to noise ratio (or sensitivity) that is practically achievable. The APD material’s electron and hole ionization coefficients (a and b respectively) are critical parameters in this regard, with very disparate values of a and b necessary to minimise this excess noise. Here, the analysis of thirteen complementary p-i-n/n-i-p diodes shows that alloying GaAs with ≤ 5.1 % Bi dramatically reduces b while leaving a virtually unchanged—enabling a 2 to 100 fold enhancement of the GaAs a/b ratio while extending the wavelength beyond 1.1 µm. Such a dramatic change in only b is unprecedented in a dilute alloy and is attributed to the Bi-induced increase of the spin-orbit splitting energy (∆so). Valence band engineering in this way offers a novel route to enable low noise semiconductor APDs to be developed.


DTP 2018-19 University of Sheffield

Engineering and Physical Sciences Research Council

Find out more...

DTA - University of Sheffield

Engineering and Physical Sciences Research Council

Find out more...

Royal Academy of Engineering - RF1516\15\43 [Richards]

RCUK | Engineering and Physical Sciences Research Council (EPSRC) - EP/N020715/1 [Tan]



There is no personal data or any that requires ethical approval


The data complies with the institution and funders' policies on access and sharing

Sharing and access restrictions

The data can be shared openly

Data description

  • The file formats are open or commonly used

Methodology, headings and units

  • Headings and units are explained in the files