Ion-Cut Transfer of InP-Based High Electron Mobility Transistors

Abstract

The ion-cut transfer of InP-based transistors onto sapphire via adhesive bonding was successfully demonstrated. In this study, high-speed modulation-doped field effect transistor layers, or MODFETs, were first epitaxially grown on InP bulk substrates. The MODFET layers were then transferred onto sapphire using one of three methods: (A) substrate removal through polishing and etching, (B) conventional ion-cutting, and (C) patterned ion-cutting or masked ion-cutting. Following layer transfer, transistors were fabricated at low temperatures (<150°C) and characterized using I-V and C-V measurements. Transistors transferred by conventional ion-cutting method were proven to be unsuitable for device fabrication. We found, however, that transistors could be successfully fabricated using the substrate removal or masked ion-cutting methods, both of which avoid ion-implantation related damage directly in the device region. The transferred transistors were well-behaved with a high field-effect mobility (μ average > 4000 cm2/V-s). The advantages of patterned ion-cutting over conventional substrate removal method include less variation between fabricated devices, slightly higher mobility likely due to lower etch pit density, and the potential recycling of the original donor substrate.