High opto-electronic quality n-type single-crystalline-like GaAs thin films on flexible metal substrates

Abstract

In this report, we present a detailed study of the microstructural and opto-electronic properties of single-crystalline-like n-type GaAs thin films directly grown on inexpensive flexible metal substrates by metal–organic chemical vapor deposition (MOCVD). The ion-beam-assisted deposition technique (IBAD) was used to obtain highly oriented single-crystalline-like buffer templates on polycrystalline metal substrates. Single-crystalline-like n-type GaAs films were achieved with sharp biaxial texture and strong (00l) crystallographic orientation. Controllable n-doping from 10¹⁶–10¹⁹ cm⁻³ was achieved using silane (SiH₄) as the dopant precursor. The GaAs films were granular with a wide distribution of grain sizes ranging from 1 to 4 μm. Strong optical photoluminescence at room temperature was obtained and the peak intensity increased with increasing doping level. Electron mobility values as high as 1320 cm² V⁻¹ s⁻¹ were obtained, one of the highest reported so far for GaAs films grown directly on unconventional substrates. Unlike GaAs on wafer substrates, the electron mobility of single-crystalline-like GaAs films significantly increased with doping which appears to be controlled by the electrical properties of the grain boundaries. High-mobility n-GaAs films on low-cost metal substrates are promising for flexible electronic and photonic device applications.