Fabrication of Germanium-on-insulator in a Ge wafer with a crystalline Ge top layer and buried GeO2 layer by oxygen ion implantation

Abstract

The paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by Oxygen ion implantation of an undoped Ge wafer of orientation (100). O+ ions (energy 200 keV) were implanted to a fluence of 1.9 × 1018 ions-cm−2 and the implanted wafer was subjected to Rapid Thermal Annealing. The resulting wafer has a top crystalline Ge layer of ~ 220 nm thickness and resistivity ≈32 Ohm-cm and a buried Oxide layer (BOX) of crystalline GeO2 (thickness ≈0.62 μm). The crystalline GeO2 layer has hexagonal crystal structure with lattice constants close to the standard values. Raman Spectroscopy and cross-sectional electron microscopy established that the top Ge layer was recrystallized during annealing with a residual tensile strain of around +0.4% and an estimated dislocation density of 2.7 × 107cm−2. The crystallinity and electrical characteristics of the top layer and the quality of the BOX layer are such that it can be utilized for device fabrication.