Characterization of GaN-based lateral polarity heterostructures

GaN-based lateral polarity heterostructures (LPH) were grown on sapphire substrates using molecular beam epitaxy. The LPH samples consist of periodical N-face (000-1) (grown directly on Al2O3) and Ga-face (0001) (grown on a AN bufferlayer) GaN stripes. The GaN-based LPH have been characterized using surface sensitive techniques. The GaN-based LPH consist of smooth Ga-face (0.4 nm RMS) and N-face regions of higher roughness (7 nm RMS) with small (<70 nm as measured by atomic force microscopy) and well-defined inversion domain boundary regions (IDBR). Further investigations have been performed by photoelectron emission microscopy (PEEM), photoelectron spectroscopy and cathodoluminescence to gain information about the surface composition including surface adsorbates as well as electronical and optical properties. PEEM reveals a "perfect" striped pattern with alternating Ga-and N-face regions with the desired periodicity over the entire field of view and, after thermal desorption of adsorbates well-defined IDBRs. In addition we found evidence for an increased chemical reactivity of the IDBs with oxygen.