Photoluminescence and Photoconductivity Dynamics in Semi-Insulating Epitaxial GaN Layers
نویسندگان
چکیده
The transients of fast free-carrier recombination and of multi-trapping processes due to different species of defects have been investigated by photoluminescence and by contact and microwave photoconductivity. Three distinct stages of relaxation, namely, of stimulated emission, of recombination due to point defects and capture into trapping centers associated with dislocations, and a non-exponential stage with a stretched-exponent asymptotic decay ascribed to dislocations mediated multi-trapping were distinguished by correlated examination of time-resolved photoluminescence and photoconductivity transients.
منابع مشابه
Semi-insulating GaN substrates for high-frequency device fabrication
Thick c-plane unintentional doped and iron-doped GaN substrates were grown by hydride vapor phase epitaxial technique on sapphire substrates. The morphology and crystalline quality of the freestanding samples show no evident degradation due to iron doping. Low-temperature photoluminescence measurements show reduction of the exciton-bound to neutral impurities band intensities with iron doping i...
متن کاملAnisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using double AlN buffer layers.
We report the anisotropic structural and optical properties of semi-polar (11-22) GaN grown on m-plane sapphire using a three-step growth method which consisted of a low temperature AlN buffer layer, followed by a high temperature AlN buffer layer and GaN growth. By introducing double AlN buffer layers, we substantially improve the crystal and optical qualities of semi-polar (11-22) GaN, and si...
متن کاملCHARACTERIZATION OF NATIVE VACANCIES IN EPITAXIAL GaN AND ZnSe SEMI- CONDUCTOR LAYERS BY POSITRON ANNIHILATION SPECTROSCOPY
Point defects in epitaxial GaN and ZnSe semiconductor layers have been studied using a low-energy positron beam. Ga vacancies are found to be present in n-type GaN grown by metal organic chemical vapor deposition, where the conductivity is due to residual oxygen. When n-type silicon impurity doping is done, clearly less vacancies are observed. In Mgdoped p-type and semi-insulating materials the...
متن کاملInfluence of dopants and substrate material on the formation of Ga vacancies in epitaxial GaN layers
We have applied a low-energy positron beam and secondary ion mass spectrometry to study defects in homoepitaxial and heteroepitaxial GaN layers. Positron experiments reveal high concentrations of Ga vacancies in nominally undoped n-type GaN, where the conductivity is due to unintentional oxygen incorporation. Ga vacancies are observed in both homoepitaxial and heteroepitaxial layers, indicating...
متن کاملAnalysis of the Efficient High-Temperature In Situ Photoluminescence from GaN Layers during Epitaxial Growth
Photoluminescence (PL) in GaN or InGaN layers monitored during epitaxial growth at high temperatures permits a quasi-continuous in situ characterization of opto-electronic properties. Therefore, epitaxial parameters can now be optimized at the earliest possible stage. A pulsed and high-power UV laser was required for PL excitation at high temperatures. Herein, the underlying nonlinear mechanism...
متن کامل