The Nonradiative Properties of Self‐Trapped Holes in Ultra‐Wide Bandgap Gallium Oxide Film

Abstract

The photoluminescence (PL) of self‐trapped holes (STH) in ultra‐wide bandgap β‐Ga2O3 is commonly its most dominant light emission and is an inherent property. Thus, gaining knowledge of the crystal dynamics that impact the PL properties is vital to sensor and other technologies. The PL, Raman‐phonons, and their interactions are studied at an extreme temperature range of 77–622 K. The PL is studied up to the bandgap value of ≈5 eV. It is found that the high‐energy Raman modes provide a major route to the nonradiative process of the PL via STH–phonon interaction with an activation energy of 72 meV. This dynamic is modeled with the configurational coordinate scheme at the strong phonon coupling limit. The exceptionally broad Gaussian PL linewidth manifests this coupling. The weak temperature response of the PL energy peak position indicates that the STH has characteristics of a deep‐level defect. This contrasts with the large redshift of ≈220 meV of the optical gap of the film, ascertained from transmission. Unlike the temperature response of the high‐energy phonons, the behavior of the low‐energy phonons is found to follow the Bose–Einstein population increase, indicating no strong interaction with the STH.