Nickel, N. H.; Mignani, N.; Rappich, J.: Metastable changes in the dark conductivity of undoped and Carbon doped β-Ga2O3. Physica Status Solidi B early view (2025), p. 2400471
10.1002/pssb.202400471
Open Access Version (externer Anbieter)
Abstract:
Measurements of the electrical dark conductivity σD of undoped and carbon-doped β-Ga2O3 thin films reveal a metastable increase upon illumination with sub-bandgap light. In the relaxed state, σD shows activated behavior for T > 250 K with an activation energy of 0.68 and 0.63 eV for undoped and C-doped β-Ga2O3, respectively. For T < 250 K, σD approaches a constant value of ≈6 × 10−12 Ω−1 cm−1. Illumination with sub-bandgap light results in an increase of the dark conductivity by up to 6 orders of magnitude. This state is metastable and relaxes with time. The data indicate the presence of a broad distribution of localized states in the bandgap. The time and temperature dependence of the relaxation is investigated for doped and undoped samples. The data can be described by a sum of two and three stretched exponential decays for undoped and carbon-doped β-Ga2O3, respectively. From the time constants of the decays, the energetic depth of the localized defect states is estimated.