Zero-field time-of-flight characterization of minority-carrier transport in heavily carbon-doped GaAs

• Published in: Journal of applied physics 1993-06, Vol.73 (11), p.7471-7477
• Main Authors: COLOMB, C. M, STOCKMAN, S. A, GARDNER, N. F, CURTIS, A. P, STILLMAN, G. E, LOW, T. S, MARS, D. E, DAVITO, D. B
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Physics
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.353991

Minority-carrier electron-diffusion coefficients and lifetimes have been measured in heavily doped p-type GaAs using the zero-field time-of-flight (ZFTOF) technique. The materials studied included C-doped GaAs grown by molecular-beam epitaxy (MBE) using graphite as the dopant source, C-doped GaAs grown by metalorganic chemical-vapor deposition (MOCVD) using CCl4 as the dopant source, and Be-doped GaAs grown by MBE. Room-temperature photoluminescence intensity measurements were made on the structures and the results are compared with ZFTOF measurements of lifetime. The graphite-doped material (p∼1019 cm−3) exhibited diffusion lengths of less than 1000 Å. MOCVD-grown C-doped GaAs, which was optimized by adjusting the growth conditions to maximize the room-temperature photoluminescence intensity, had diffusion lengths comparable to those measured in Be-doped GaAs for hole concentrations of 1×1019 and 5×1019 cm−3. Comparison of photoluminescence intensities also suggests that addition of In to very heavily doped MOCVD-grown GaAs (p≳1020 cm−3) to eliminate the lattice mismatch with respect to the substrate does not result in an improvement in lifetime.