Experimental Study of Pressure Influence on Tunnel Transport into 2DEG

TL;DR

This study investigates how high pressure affects tunneling properties in an Al/δ-Si-GaAs system at cryogenic temperatures, revealing pressure-dependent barrier height, impurity density reduction, and potential metal-insulator transition in 2DEG.

Contribution

It provides new experimental data on pressure effects on tunneling and impurity density in Al/δ-Si-GaAs systems, highlighting possible phase transition points.

Findings

Barrier height is 0.86 eV at zero pressure with a pressure coefficient of 3 meV/kbar.

Charged impurity density decreases from 4.5×10^{12} to 3.8×10^{12} cm^{-2} at 1.5 GPa.

Metal-insulator transition may occur around 2 GPa.

Abstract

We present the concept and the results of pilot measurements of tunneling in a system {Al/$\delta_{Si}$-GaAs} under pressure up to 2 GPa at 4.2 K. The obtained results may indicate the following: the barrier height for {Al/$\delta$-GaAs} equals to 0.86 eV at P=0 and its pressure coefficient is $3 meV/kbar$; charged impurity density in the delta-layer starts to drop from $4.5\times 10^{12} cm^{-2}$ down to $3.8\times 10^{12} cm^{-2}$ at about 1.5 GPa; metal-insulator transition may occur in 2DEG at about 2 GPa.