Novel high quality GeSn alloys for mid-infrared photodetectors
Abstract
Intense research interest in GeSn alloys in recent years has been fuelled by their potential for efficient light absorption in the near-to-mid infrared (IR), the possibility of mid-IR lasers, and their ready compatibility, including integration, with Si fabrication. However, the Sn solubility in Ge is only 0.5 at% and hence non-equilibrium methods must be used to produce high quality alloys with high Sn content. Conventionally, CVD has been the preferred preparation method but several challenges in producing good quality material have made efficient room temperature IR photodetectors (and lasers) out to 4 µm elusive. Recently, we developed a new preparation method involving Sn ion implantation into Ge followed by pulsed laser melting (PLM) to produce both thin (strained) and thick (unstrained) alloy layers with Sn concentrations beyond 15 at%. Initial results indicate promising properties in terms of material quality and IR optical behavior. We have also developed a dual PLM process (yet to be fully tested) for minimizing ubiquitous threading defects in unstrained high-Sn-content alloys. This has the potential for substantially improving the quality of both CVD-grown and implanted alloy films. This proposal is therefore focused on optimizing the material quality of alloys grown on both Ge and Si substrates using this implantation/PLM method, employing the dual PLM process to minimize defects in both CVD-grown and implanted alloys, doping them by ion implantation, and fully characterizing their physical and optical properties using a multitude of techniques. The outcome is material of sufficient quality to realize high performance near-to-mid infrared photodetectors operating beyond 4 µm at room temperature. If successful, this could lead to the first efficient high-resolution mid-IR imaging array integrated onto Si that operates at room temperature.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 24, 2019
- Source ID
- FA23861814078
Entities
People
- Jim Williams
Organizations
- Air Force Office of Scientific Research
- Australian National University
- United States Air Force