Hexagonal Wurtzite Type Epitaxial Layer with a Low Alkali-Metal Concentration
Tech ID: 23657 / UC Case 2008-658-0
A method to produce hexagonal würtzite type epitaxial layers possessing low alkali-metal concentration.
A high-quality substrate is essential for fabrication of GaN devices, which has led to various approaches for growing GaN single crystal substrates. In most approaches, alkali-metals are added to the growth system, causing the grown GaN crystals to contain high concentrations of alkali-metals. This high concentration of alkali metals severely increases the likelihood that alkali-metals will diffuse into the epitaxial layers, having a negative impact on the electrical properties and performance of devices.
Researchers at the University of California, Santa Barbara have developed a method to produce hexagonal würtzite type epitaxial layers possessing low alkali-metal concentration. While incorporation of alkali-metals is essential to the growth process, they have a negative impact on device properties. We have found that the diffusion of alkali-metals into the epitaxial layer strongly depends on the crystal plane of the substrate and therefore can be effectively suppressed. This method produces bow-free GaN substrates containing low structural defect densities in a cost effective manner, allowing manufacturers of both devices and substrates to benefit.
- Low alkali-metal diffusion
- Improved device performance
- LEDs and Laser Diodes
- High Electron Mobility Transistors (HEMTs)
- Power switching devices
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