Research Applications in III-nitrides with Cathodoluminescence Unitized Systems
阴极荧光联合分析系统在III族氮化物研究中的应用

The optical properties of several typical III-nitride semiconductors were investigated by cathodoluminescence (CL) unitized systems.The CL unitized systems are combined with a thermal field-emission scanning electron microscopy (JEOL JSM-7000F) and a high performance CL spectroscopy (Gatan Mono CL3) equipped LN-cooling stage.Two aspects can be obtained from the measurements: (1) CL spectrum.Using a UV-visible CL spectrum system,the optical properties of unintentionally-doped and Mg-doped AlxGa1-xN films grown on c-plane sapphire are analyzed.This analysis indicates that the peak intensity of near band edge emission at 4.6eV increases proportionally with excitation power density.However,that the intensity of the 3.9eV band originated from a Mg-doped impurity-level shows saturation independence with excitation power density.Furthermore,the CL from InN films is measured with a near infrared (NIR) CL system,which proves that the optical band gap of InN locates at 0.77eV. (2) CL mapping.The CL unitized systems can give the luminescence area at different wavelength in the UV-visible range.The free-standing GaN substrates grown by hydride vapor phase epitaxy are analyzed combining SEM and CL mapping methods.The edge type dislocations are observed under the surface using CL mapping instead of SEM.The type,distribution,and luminescence properties of dislocations are studied.