Effect of carrier gas and substrate misorientation on the structural and optical properties of m-plane InGaN/GaN light-emitting diodes

The properties of Si-doped GaN (GaN Si) thin films and InGaN/GaN light-emitting diodes (LEDs) grown by metalorganic chemical vapor deposition on free-standing {1 0 (1) over bar 0} m-plane GaN substrates were investigated with regard to carrier gas and substrate misonentation toward the [0 0 0 (1) over bar ]c(-) direction The surface morphology of the GaN Si thin films and the LEDs was found to be strongly dependent on the choice of carrier gas and substrate misonentation Growth of GaN Si thin films on nominally on-axis substrates produced surfaces with a high density of four-sided pyramidal hillocks regardless of the composition of the carrier gas In contrast growth of GaN Si thin films on substrates with misonentation angles greater than 0 7 yielded moderately to severely faceted surfaces when grown with H(2) as the carrier gas and atomically smooth surfaces when grown with N(2) as the carrier gas Although the surface morphology varied significantly with substrate misonentation the average indium mole fraction in the InGaN-based quantum wells the output power of the LEDs the electroluminescence (EL) peak wavelength and the EL linewidth showed little dependence on substrate misonentation Substrates with misonentation angles of about 1 degrees were successfully used to grow LEDs with Improved surface morphology but similar optical properties compared to LEDs grown on nominally on-axis substrates (C) 2010 Elsevier B V All rights reserved