The role of defects in fluorescent silicon carbide layers grown by sublimation epitaxy

S Schimmel,R Liljedahl,V Jokubavicius,Y Ou,P Hens,P Wellmann,M K Linnarsson,M Kaiser,M Syväjärvi,J Sun,H Ou

doi:10.1088/1757-899x/56/1/012002

Abstract

Donor-acceptor co-doped SiC is a promising light converter for novel monolithic all-semiconductor white LEDs due to its broad-band donor-acceptor pair luminescence and potentially high internal quantum efficiency. Besides sufficiently high doping concentrations in an appropriate ratio yielding short radiative lifetimes, long nonradiative lifetimes are crucial for efficient light conversion. The impact of different types of defects is studied by characterizing fluorescent silicon carbide layers with regard to photoluminescence intensity, homogeneity and efficiency taking into account dislocation density and distribution. Different doping concentrations and variations in gas phase composition and pressure are investigated.

Highlights

Donor-acceptor co-doped SiC was first recognized as a potential light converter for a novel monolithic all-semiconductor white LED by Kamiyama et al in 2006 [1]
The layers are commonly grown by the Fast Sublimation Growth Process (FSGP) [2] which is highly suitable for the growth of high quality thick epitaxial layers with reasonable growth rate
As the considerations above indicate that short nonradiative lifetimes may be a critical issue for the light conversion efficiency of f-SiC layers, this work will focus on the role of different types of defects in fluorescent silicon carbide

Summary

Introduction

Donor-acceptor co-doped SiC was first recognized as a potential light converter for a novel monolithic all-semiconductor white LED by Kamiyama et al in 2006 [1]. The internal quantum efficiency (IQE) of typical samples lags far behind the theoretically predicted high efficiencies, even though a large range of doping concentrations and ratios has been studied. This suggests that the IQE is severely affected by short nonradiative lifetimes. According to XRD measurements, the epitaxial layers grown by FSGP may even show an improved crystalline quality with regard to the substrate [2] and the charge carrier lifetime is usually quite high, typically about 2 μs [3]. As the considerations above indicate that short nonradiative lifetimes may be a critical issue for the light conversion efficiency of f-SiC layers, this work will focus on the role of different types of defects in fluorescent silicon carbide

Experimental

Static RT

Results and Discussion

Conclusion