Temperature dependence of ambipolar diffusion in silicon-on-insulator

TL;DR

This study investigates how ambipolar diffusion in silicon-on-insulator varies with temperature, revealing the influence of defects and stress on carrier mobility across a range of 90 K to 400 K.

Contribution

It provides detailed measurements of temperature-dependent ambipolar diffusivity in silicon-on-insulator, highlighting the effects of defects and residual stress.

Findings

Ambipolar diffusivity decreases with temperature from 250 K to 400 K.

Cooling from 250 K to 90 K further reduces diffusivity due to defects and stress.

No significant density dependence of ambipolar diffusivity was observed.

Abstract

Spatiotemporal dynamics of electron-hole pairs locally excited in a silicon-on-insulator structure by indirect interband absorption are studied by measuring differential transmission caused by free-carrier absorption of a probe pulse tuned below the bandgap, with 200-fs temporal and 3-micrometer spatial resolution. From sample temperatures of 250 K to 400 K, the ambipolar diffusivity decreases, and is similar to reported values of bulk silicon. Cooling the sample from 250 K to 90 K, a decrease of ambipolar diffusivity is observed, indicating important influences of defects and residual stress on carrier diffusion. No detectable density dependence of ambipolar diffusivity is observed.