High-quality GeSn Layer with Sn Composition up to 7% Grown by Low-temperature Magnetron Sputtering for Optoelectronic Application.

Yang Yang,Dong Dong,Miao Miao,Xuan Xuan,Wang Wang,Hu Hu

doi:10.3390/ma12172662

Abstract

In this paper, a high-quality sputtered-GeSn layer on Ge (100) with a Sn composition up to 7% was demonstrated. The crystallinity of the GeSn layer was investigated via high-resolution X-ray diffraction (HR-XRD) and the strain relaxation degree of the GeSn layer was evaluated to be approximately 50%. A novel method was also proposed to evaluate the averaged threading dislocation densities (TDDs) in the GeSn layer, which was obtained from the rocking curve of GeSn layer along the (004) plane. The photoluminescence (PL) measurement result shows the significant optical emission (1870 nm) from the deposited high-quality GeSn layer. To verify whether our deposited GeSn can be used for optoelectronic devices, we fabricated the simple vertical p-i-n diode, and the room temperature current–voltage (I–V) characteristic was obtained. Our work paves the way for future sputtered-GeSn optimization, which is critical for optoelectronic applications.

Highlights

GeSn alloys have been shown the capability to become a real direct bandgap material with a Sn composition of 10% [1,2,3], which makes it a promising optical gain medium for group IV light sources [4,5,6]
We propose a novel method to obtain the threading dislocation densities TDDs of GeSn layers from GeSn
A high-quality GeSn layer with a Sn content up to 7% was successfully grown on a Ge (100) substrate via magnetron co-sputtering

Summary

Introduction

GeSn alloys have been shown the capability to become a real direct bandgap material with a Sn composition of 10% [1,2,3], which makes it a promising optical gain medium for group IV light sources [4,5,6]. The epitaxial growth of high-Sn-composition GeSn with high material quality is challenging because the solid solubility of Sn in Ge or Ge in Sn is less than 1%. Ge makes Sn more likely to immigrate to the surface of the GeSn film during epitaxial growth and thermal treatment [7,8,9,10,11]. Several techniques such as chemical vapor deposition (CVD) [12,13,14], molecular beam epitaxy (MBE) [15,16,17], and magnetron sputtering [18,19,20,21,22] have been employed to achieve the crystalline GeSn layers. Lasing from GeSn micro disks with a Sn composition up to

Methods

Results

Conclusion