Observation of abrupt first-order metal-insulator transition in GaAs-based two-terminal device

TL;DR

This study reports an abrupt first-order metal-insulator transition in Be-doped GaAs induced by electric field, observed at room temperature at very low hole densities, with implications for understanding high-field breakdown in semiconductors.

Contribution

It demonstrates the existence of an intrinsic, abrupt first-order MIT in GaAs without structural change, induced by electric field at room temperature, revealing new insights into semiconductor breakdown phenomena.

Findings

Abrupt MIT observed at low hole density (~5x10^{14} cm^{-3})

No structural phase transition accompanies the MIT

MIT occurs at temperatures up to approximately 440K

Abstract

An abrupt first-order metal-insulator transition (MIT) as a jump of the density of states is observed for Be doped GaAs, which is known as a semiconductor, by inducing very low holes of approximately n_p=5x10^{14} cm^{-3} into the valence band by the electric field; this is anomalous. In a higher hole doping concentration of n_p=6x10^{16} cm^{-3}, the abrupt MIT is not observed at room temperature, but measured at low temperature. A large discontinuous decrease of photoluminescence intensity at 1.43 eV energy gap and a negative differential resistance are also observed as further evidence of the MIT. The abrupt MIT does not undergo a structural phase transition and is accompanied with inhomogeneity. The upper limit of the temperature allowing the MIT is deduced to be approximately 440K from experimental data. The abrupt MIT rather than the continuous MIT is intrinsic and can explain the "breakdown" phenomenon (unsolved problem) incurred by a high electric field in semiconductor devices.