Abstract
The epitaxy of high-power gallium nitride (GaN) light-emitting diode (LED) on amorphous silicon carbide (a-SixC1−x) buffer is demonstrated. The a-SixC1−x buffers with different nonstoichiometric C/Si composition ratios are synthesized on SiO2/Si substrate by using a low-temperature plasma enhanced chemical vapor deposition. The GaN LEDs on different SixC1−x buffers exhibit different EL and C-V characteristics because of the extended strain induced interfacial defects. The EL power decays when increasing the Si content of SixC1−x buffer. The C-rich SixC1−x favors the GaN epitaxy and enables the strain relaxation to suppress the probability of Auger recombination. When the SixC1−x buffer changes from Si-rich to C-rich condition, the EL peak wavelengh shifts from 446 nm to 450 nm. Moreover, the uniform distribution contour of EL intensity spreads between the anode and the cathode because the traping density of the interfacial defect gradually reduces. In comparison with the GaN LED grown on Si-rich SixC1−x buffer, the device deposited on C-rich SixC1−x buffer shows a lower turn-on voltage, a higher output power, an external quantum efficiency, and an efficiency droop of 2.48 V, 106 mW, 42.3%, and 7%, respectively.
Highlights
Yoshida et al employed the AlN film as buffer layer to improve the performance of strain relaxation[9]
The epitaxy of gallium nitride (GaN) light-emitting diode (LED) upon the a-SixC1−x buffer grown by low-temperature PECVD on the SiO2/Si substrate is demonstrated
The C-V analysis declares that the area density of defects is decreased from 2.87 × 1010 cm−2 to 1.09 × 1010 cm−2 when Si-rich SiC buffer replaces to C-rich one when the released strain effectively reduces the defects in the GaN LED grown on lattice matched C-rich SixC1−x buffer
Summary
Yoshida et al employed the AlN film as buffer layer to improve the performance of strain relaxation[9]. Boo et al reported that the cubic SiC buffer layer grown on (111)-oriented Si wafer by using the chemical vapor deposition (CVD) can be employed to deposit the hexagonal GaN thin films[23]. The effects on the strain, quantum efficiency, power, and droop characteristics for the GaN LED grown on SiC/SiO2/Si substrate are compared when the SixC1−x film with different C/Si composition ratios is used as the buffers for the GaN LED growth. We further emphasize on the successful epitaxy of the GaN LED deposited on the a-SiC buffer without performance degradation, and develop the procedure for transferring the flexible GaN LED on a-SixC1−x buffer from the SiO2/Si substrate to a copper plate for future industrial application. The experimental results show that the performance of the GaN LED is not degraded before and after immersing in the buffer oxide etching solution for separating the GaN LED with a-SixC1−x buffer from SiO2/Si wafer
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