Influence of encapsulation temperature on Ge:P delta-doped layers

TL;DR

This study investigates how encapsulation temperature affects dopant confinement and electrical performance in Ge:P delta-doped layers, finding an optimal growth temperature that balances quality and dopant stability.

Contribution

It provides a systematic analysis of encapsulation temperature effects on Ge:P delta-doped layers, identifying optimal conditions for high-quality, minimally redistributed dopant layers.

Findings

Higher growth temperatures increase electrical properties but also dopant segregation.

Step-flow growth at 530°C offers the best compromise between quality and dopant confinement.

Achieved electron mobility of ~128 cm^2/Vs and phase coherence length of ~180 nm at 4.2 K.

Abstract

We present a systematic study of the influence of the encapsulation temperature on dopant confinement and electrical properties of Ge:P delta-doped layers. For increasing growth temperature we observe an enhancement of the electrical properties accompanied by an increased segregation of the phosphorous donors, resulting in a slight broadening of the delta-layer. We demonstrate that a step-flow growth achieved at 530 C provides the best compromise between high crystal quality and minimal dopant redistribution, with an electron mobility ~ 128 cm^2/Vs at a carrier density 1.3x10^14 cm-2, and a 4.2 K phase coherence length of ~ 180 nm.