Diffusion properties of electrons in GaN crystals subjected to electric and magnetic fields

TL;DR

This study investigates how electric and magnetic fields influence electron diffusion in GaN crystals, revealing temperature and impurity effects on diffusion behavior and potential for improved electronic device design.

Contribution

It provides new insights into the diffusion tensor behavior of hot electrons in GaN under combined electric and magnetic fields across various conditions.

Findings

Diffusion tensor components show non-monotonic behavior at low temperature and impurity levels.

Magnetic fields significantly influence electron diffusion processes.

Higher temperature and impurity levels lead to more monotonic diffusion behavior.

Abstract

We studied the diffusion coefficient of hot electrons of GaN crystals in moderate electric (1...10 kV/cm) and magnetic (1...4 T) fields. Two configurations, parallel and crossed fields, are analysed. The study was carried out for compensated bulk-like GaN samples at different lattice temperatures (30...300 K) and impurity concentrations (10^16..10^17 cm^{-3}). We found that at low lattice temperatures and low impurity concentrations, electric-field dependencies of the transverse-to-current components of the diffusion tensor are non-monotonic for both configurations, while the diffusion processes are greatly controlled by the magnetic field. With an increase of the lattice temperature or the impurity concentration, the behaviour of the diffusion tensor becomes more monotonous and less affected by the magnetic field. We showed that such behaviour of the diffusion processes is due to the distinct kinetics of the hot electrons in polar semiconductors with strong electron-optical phonon coupling. We suggest that measurements of the diffusion coefficient of the electrons subjected to electric and magnetic fields facilitate the identification of features of different electron transport regimes and the development of more efficient devices and practical applications.