Deep levels in high resistivity GaN epilayers grown by MOCVD

Abstract

PACS 71.55.Eq, 81.15.Gh Undoped high resistivity (HR) GaN epilayers were grown on (0001) sapphire substrate by metalorganic chemical vapor deposition (MOCVD). Thermally stimulated current (TSC) and resistivity measurements have been carried out to investigate deep level traps. Deep levels with activation energies of 1.06eV and 0.85eV were measured in sample 1. Gaussian fitting of TSC spectra showed five deep levels in different samples.

Analysis of doping concentration and composition in wide bandgap AlGaN:Si by wavelength dispersive x-ray spectroscopy

“…As indicated by the horizontal lines, this result shows that the Si incorporation of the investigated samples is independent of the composition of the sample and only depends on the SiH 4 /III ratio that was used during the growth. Junxue et al [25] proposed an increasing Si incorporation with increasing Al content, which they attributed to an increasing rate of parasitic prereactions in the gas phase with increasing TMAl partial pressure. However, as the TMAl partial pressure was kept constant for the samples in the present study and the variation of the composition was achieved by varying TMGa partial pressure, a negligible change in the amount of gas phase prereactions is expected, leading to a Si incorporation independent of the Al composition.…”

Local Piezoelectric Behavior of Potassium Sodium Niobate Prepared by a Facile Synthesis via Water Soluble Precursors

“…However, the high cost and easiness to hydrolysis of niobium alkoxides are limiting factors of these processes for scaling up applications . Niobium (V) oxide is considered a good alternative as Nb precursor for its low cost and for the possibility to obtain metal complexes with chelating species in water The principle of this method is that hydroxycarboxylic acids, amino acids, or some other natural organic compounds are used to protect and stabilize high valence metal ions, activating them to enhance solubility and reactivity in water. On the other hand, the many steps involved in the preparation process with niobium oxide reagent, are time consuming and imply drawbacks for the use of hydrofluoric acid (HF) in order to prepare niobic acid or at high temperature .…”