Structural and Electrical Characterization of 2" Ammonothermal Free-Standing GaN Wafers. Progress toward Pilot Production.

Daryl Key,Chuan-Wei Tsou,Edward Letts,Tadao Hashimoto,Shyh-Chiang Shen,Russell Dupuis,Mi-Hee Ji,Theeradetch Detchprohm,Marzieh Bakhtiary-Noodeh

doi:10.3390/ma12121925

Abstract

Free-standing gallium nitride (GaN) substrates are in high demand for power devices, laser diodes, and high-power light emitting diodes (LEDs). SixPoint Materials Inc. has begun producing 2” GaN substrates through our proprietary Near Equilibrium AmmonoThermal (NEAT) growth technology. In a single 90 day growth, eleven c-plane GaN boules were grown from free-standing hydride vapor phase epitaxy (HVPE) GaN substrates. The boules had an average X-ray rocking curve full width at half maximum (FWHM) of 33 ± 4 in the 002 reflection and 44 ± 6 in the 201 reflection using 0.3 mm divergence slits. The boules had an average radius of curvature of 10.16 ± 3.63 m. The quality of the boules was highly correlated to the quality of the seeds. A PIN diode grown at Georgia Tech on a NEAT GaN substrate had an ideality factor of 2.08, a high breakdown voltage of 1430 V, and Baliga’s Figure of Merit of >9.2 GW/cm2. These initial results demonstrate the suitability of using NEAT GaN substrates for high-quality MOCVD growth and fabrication of high-power vertical GaN switching devices.

Highlights

Gallium Nitride (GaN) semiconductor devices including light-emitting diodes (LEDs), laser diodes, and power transistors have brought about great technological change
The aim of this work is to bring low-defect true-bulk GaN substrates to market with a clear path to lowering cost using our proprietary near equilibrium ammonothermal (NEAT) method
We found that it was more likely that the grown crystal would be lower quality than the seed as measured by the full width at half maximum (FWHM) of the X-ray rocking curve

Summary

Introduction

Gallium Nitride (GaN) semiconductor devices including light-emitting diodes (LEDs), laser diodes, and power transistors have brought about great technological change. White LEDs were invented in 1994 by adding a yellow phosphor to GaN-based blue LEDs invented the year prior. LEDs had tremendous advantages over incumbent lighting technologies including efficiency, lifetime, color, and size. These impacts were recognized in 2014 when the Nobel Prize in Physics was awarded to the inventers of the GaN-based blue and subsequent white LED [1]. Adoption of LEDs is decreasing the energy used for lighting. In 2015, the LED-installed stock penetration of 6% in the U.S resulted in an annual saving of 82 billion kWh. In 2035, the LED-installed stock penetration is projected to be 86%

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