Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

Abstract

This paper reports an efficient method to improve the crystal quality of GaN Gunn diode with AlGaN hot electron injecting layer (HEI). An evident reduction of screw dislocation and edge dislocation densities is achieved by the strain management and the enhanced lateral growth in high temperature grown AlGaN HEI layer. Compared with the top hot electron injecting layer (THEI) structure, the bottom hot electron injecting layer (BHEI) structure enhances the crystal quality of transit region due to the growth sequence modulation of HEI layer. A high Hall mobility of 2934 cm2/Vs at 77 K, a nearly flat downtrend of Hall mobility at the temperature ranging from 300 to 573 K, a low intensity of ratio of yellow luminescence band to band edge emission, a narrow band edge emission line-width, and a smooth surface morphology are observed for the BHEI structural epitaxy of Gunn diode, which indicates that AlGaN BHEI structure is a promising candidate for fabrication of GaN Gunn diodes in terahertz regime.

Reliable GaN-Based THz Gunn Diodes With Side-Contact and Field-Plate Technologies

“…Lee et al showed in [9] that the Gunn diode with 550 nm transit length is capable to achieve a 500 GHz signal of 2.61 W with 2.27% efficiency under 22 V DC and 5 V RF condition. In [10], an efficient method to improve the crystal quality of GaN Gunn diode with AlGaN hot electron injecting layer on SiC substrate was reported. Multi-channel Gunn diode, which is realized by containing multiple AlGaN/GaN heterostructures as GaN-based HEMT-like planar Gunn diode improves the output power and the characteristics at a higher frequency, was proposed in [11].…”