Crystal and electrical properties of polycrystalline In1−xGaxAs thin films directly formed on insulators

• Polycrystalline InGaAs thin films are investigated in the most detailed and comprehensive manner to date. • The composition and deposition temperature significantly impact the crystallinity and crystal orientations of the InGaAs layers. • For undoped InGaAs layers, increasing the In content and deposition temperature increases the electron mobility up to 310 cm −2 V−1s−1. • Sn is demonstrated to be an effective n-type dopant, which controls electron concentration within the range of 1017 to 1019 cm −3 . Polycrystalline In 1− x Ga x As thin films are promising for high-performance electronics on versatile substrates, including transistors, solar cells, optical communication devices, and infrared sensors. This study examines the effects of composition, deposition temperature, and impurity doping on the grain size, crystal orientation, nanostructure, and electrical properties of In 1− x Ga x As layers, utilizing various evaluation methods with machine learning. The results demonstrate that the composition and deposition temperature significantly influence the crystallinity and crystal orientations. Higher In compositions and deposition temperatures yield In 1− x Ga x As with enhanced crystallinity. The undoped samples exhibit n-type conduction, which is likely attributable to antisite defects. Increasing the In content and deposition temperature increases the electron concentration and mobility up to 3 × 10 18 cm −3 and 310 cm 2 V −1 s −1 , respectively. Sn is an effective n-type dopant, facilitating the control of electron concentration within the range of 10 17 –10 19 cm −3 . These findings offer valuable insights into the application of In 1− x Ga x As in high-performance electronic devices.