Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 25: Poster Session: GaN - Optical Properties & Preparation and Characterization & Devices

HL 25.21: Poster

Montag, 26. März 2012, 16:00–19:00, Poster D

Investigation of the incorporation of Mg as p-dopant in GaN grown by metal modulated epitaxy — •Thorsten Klein¹, Stephan Figge¹, Tomasz Krajewski², Marek Godlewski², and Detlef Hommel¹ — ¹Institute of Solid State Physics, University of Bremen, Germany — ²Institute of Physics, Polish Academy of Sciences, Warsaw, Poland

Group III-nitrides are of high interest for use in optoelectronic devices such as light emitting diodes or laser diodes. However, one of the main challenges remains the growth of highly p-doped GaN:Mg to achieve higher efficiencies of such devices. In our work we present an approach of low-temperature GaN-growth by metal modulated epitaxy (MME) which was reported in the literature to strongly increase the doping level up to 4×10¹⁹ cm⁻³. During MME the metal shutters (Ga, Mg) are periodically opened and closed while the N-shutter remains constantly open. This method is used to optimize the incorporation of Mg into the structure while preserving a smooth surface. The growth takes place under metal-rich conditions and is monitored in-situ by RHEED. The substrate temperature is 550 ^∘C. AFM investigations reveal RMS values of 1.9 nm. The surface shows holes with a depth of about 30 nm, in between them RMS values of 0.7 nm indicate an atomically flat surface. Hall effect measurements were performed to determine the doping level. Charge carrier densities up to 1.6×10¹⁹ cm⁻³ are achieved, which remain almost constant over a temperature range between 50 - 400 K. Activation energies of 10 - 12 meV as well as mobilities around 30 cm²/Vs indicate electron conductivity.