Amorphous selenium
(a-Se) is a large-area compatible photoconductor
that has received significant attention toward the development of
UV and X-ray detectors for a wide range of applications in medical
imaging, life science, high-energy physics, and nuclear radiation
detection. A subset of applications require detection of photons with
spectral coverage from UV to infrared wavelengths. In this work, we
present a systematic study utilizing density functional theory simulations
and experimental studies to investigate optical and electrical properties
of a-Se alloyed with tellurium (Te). We report hole and electron mobilities
and conversion efficiencies for a-Se1–xTex(x= 0, 0.03,
0.05, 0.08) devices as a function of applied field, along with band
gaps and comparisons to previous studies. For the first time, these
values are reported at high electric field (>10 V/μm), demonstrating
recovery of quantum efficiency in Se–Te alloys. A comparison
to the Onsager model for a-Se demonstrates the strong field dependence
in the thermalization length and expands on the role of defect states
in device performance.