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

TL;DR

This paper demonstrates a method to fabricate Germanium-on-Insulator wafers using oxygen ion implantation and rapid thermal annealing, producing a high-quality crystalline Ge top layer and GeO2 buried oxide suitable for device applications.

Contribution

It introduces a novel fabrication process for GeOI wafers with controlled layer properties using oxygen ion implantation and annealing.

Findings

Top Ge layer thickness of 220 nm with good crystallinity

Buried GeO2 layer of 0.62 micron with hexagonal structure

Top layer exhibits small tensile strain and low dislocation density

Abstract

The paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by Oxygen ion implantation of an undoped single crystalline Ge wafer of orientation (100). Oxygen ions of energy 200 keV were implanted. The implanted wafer was subjected to Rapid Thermal Annealing to 650 C. The resulting wafer has a top crystalline Ge layer of 220 nm thickness and Buried Oxide layer (BOX) layer of good quality crystalline Germanium oxide with thickness around 0.62 micron. The crystalline BOX layer has hexagonal crystal structure with lattice constants close to the standard values. Raman Spectroscopy, cross-sectional HRTEM with SAED and EDS established that the top Ge layer was recrystallized during annealing with faceted crystallites. The top layer has a small tensile strain of around +0.4\% and has estimated dislocation density of 2.7 x 10^{7}cm^{-2}. The thickness, crystallinity and electrical characteristics of the top layer and the quality of the BOX layer of GeO_{2} are such that it can be utilized for device fabrication.