Low temperature buffer growth for the development of vertical light emitting diodes

One key challenge with the the use of III-nitride materials in solid state lighting devices is the use on thermally and/or electrically insulating substrates. In order to transition the lift-off tehniques from laserbased processing to more benign chemical techniques, it is essential to realize the integration of chemical soluble layers into the LED-growth process. This work presents the comparison of physical and chemical vapor deposition techniques used in the growth of ZnO, one such possible isostructural buffer layer and a comparison of the materials properties of samples grown by low temperature chemical vapor deposition and pulsed laser deposition. The quality of the films was highly dependent on the growth conditions and substrate preparation. For room temperature depostion, amorphous ZnO films were observed, while completely oriented films were observed for 750°C growth. Pulsed chemical vapor deposition of the films at 175°C showed smoother polycrystalline films with c-axis texture. ZnO films were etched at room temperature demonstrating the suitability for chemical liftoff.