Buried Heterostructure of Nitride Semiconductors Revealed by Laboratory Level X-ray CTR Scattering

Abstract

We set up a laboratory level X-ray CTR measurement system using a multilayer focusing mirror and a channel-cut asymmetric Ge double-crystal for a beam squeezing and an imaging plate as a 2D detector. Even though the intensity of the laboratory X-ray is by 700 times lower than that of the synchrotron X-ray, good enough signal/background ratios were achieved by the laboratory X-ray system for a reasonable measurement time of 100 minutes. This measurement system was applied to GaN/GainN/GaN heterostructures on sapphires, which were difficult to obtain a good signal/background ratio using synchrotron X-ray CTR measurements system, and reasonable CTR data were obtained. In distributions in GaN/GainN/GaN very different from those designed were obtained.

In situ X-ray Reflectivity Measurements on Annealed InxGa1-xN Epilayer Grown by Metalorganic Vapor Phase Epitaxy

“…To investigate the phenomena that occur at different growth temperatures, to understand the growth processes, and to control the heterostructures, an MOVPE growth system for III-nitrides in an X-ray generator and a goniometer system using a laboratory-level X-ray source has been successfully designed and set up. [7][8][9] We have reported preliminary experiments of X-ray crystal truncation rod (CTR) scattering measurements for In x Ga 1Àx N growth at various growth temperatures. Moreover, we have detected, by X-ray CTR scattering measurements, crystalline indium on an In x Ga 1Àx N layer at room temperature (RT).…”

Measurement of X-ray CTR Signals from GaN/GaInN/GaN at High Temperatures Using Newly Developed Measurement System

“…Though a picture of the X-ray system and installed reactor was shown in our previous paper [1], some details of the reactor structure and the XYZ-stage are described here. Fig.…”

“…The improvements made were to use a multi-layered focusing mirror and an asymmetry-cut double-crystal to collect and squeeze the X-rays from the rotating target X-ray source and to use slits between the sample and the detector to avoid stray X-rays [1][2].…”

“…The MOVPE (metalorganic vapor phase epitaxy) reactor with two Be windows was installed to the laboratory X-ray system [1].…”