Surface Etching and Temperature Effects on SiC Electroluminescence

Abstract

Silicon carbide was the first substance reported to display electroluminescence and enabled the first blue light emitting diode (LED). While the challenges of fabrication and poor efficiency lead to alternatives being developed, recent demand for high temperature, high power electronics have brought silicon carbide back to the forefront of development and improved quality and production scale. Due to the large bandgap, it is possible for light across the visible spectrum and into ultraviolet (UV) to be emitted. The wavelength of light produced depends heavily on the inclusion of different defects and impurities. Great care is taken to minimize this to improve device performance. The ability to induce and control these defects however, could allow for a range of wavelengths to be emitted and enable different colours of LEDs or the creation of white LEDs without the need for phosphors. This thesis explores different post fabrication treatments and operating conditions that can be used to alter the luminescent intensity and spectrum of commercial devices. Chapter one will include a brief history of LED development in addition to exploring the strengths and weaknesses of silicon carbide as a light emitting material. The following chapter will cover the theory behind LED operation and the structure/properties of SiC. In chapter 4, an electrochemical etch is used to alter the emission spectrum through the formation of a nano-porous surface layer. The processed device is then used to demonstrate electroluminescence due to lateral charge diffusion in SiC for the first time Chapter 5 details the effects of operating conditions on electroluminescence with a strong focus on temperature, and chapter 6 suggests future work and possible applications.