Improving Transport Properties of GaN-Based HEMT on Si (111) by Controlling SiH4 Flow Rate of the SiNx Nano-Mask

The AlGaN/AlN/GaN high electron mobility transistor structures were grown on a Si (111) substrate by metalorganic chemical vapor deposition in combination with the insertion of a SiNx nano-mask into the low-temperature GaN buffer layer. Herein, the impact of SiH4 flow rate on two-dimensional electron gas (2DEG) properties was comprehensively investigated, where an increase in SiH4 flow rate resulted in a decrease in edge-type threading dislocation density during coalescence process and an improvement of 2DEG electronic properties. The study also reveals that controlling the SiH4 flow rate of the SiNx nano-mask grown at low temperatures in a short time is an effective strategy to overcome the surface desorption issue that causes surface roughness degradation. The highest electron mobility of 1970 cm2/V·s and sheet carrier concentration of 6.42 × 1012 cm−2 can be achieved via an optimized SiH4 flow rate of 50 sccm.

Crack-free high quality 2 μm-thick Al0.5Ga0.5N grown on a Si substrate with a superlattice transition layer

We reported the successful growth of a crack-free high-quality 2 μm-thick Al_0.5Ga_0.5N film with a smooth surface grown on planar Si by metal–organic chemical vapor deposition.

Formation of spherical-shaped GaN and InN quantum dots on curved SiN/Si surface

This paper reports the formation of GaN and InN quantum dots (QDs) with symmetric spherical shapes, grown on SiN/Si(111). Spherical QDs are grown by modulating initial growth behavior via gallium and indium droplets functioning as nucleation sites for QDs. Field-emission scanning electron microscope (FE-SEM) images show that GaN and InN QDs are formed on curved SiN/Si(111) instead of on a flat surface similar to balls on a latex mattress. This is considerably different from the structural properties of In(Ga)As QDs grown on GaAs or InP. In addition, considering the shape of the other III-V semiconductor QDs, the QDs in this study are very close to the ideal shape of zero-dimensional nanostructures. Transmission-electron microscope images show the formation of symmetric GaN and InN QDs with a round shape, agreeing well with the FE-SEM results. Compared to other III-V semiconductor QDs, the unique structural properties of Si-based GaN and InN QDs are strongly related to the modulation in the initial nucleation characteristics due to the presence of droplets, the degree of lattice mismatch between GaN or InN and SiN/Si(111), and the melt-back etching phenomenon.

Nucleation layer design for growth of a high-quality AlN epitaxial film on a Si(111) substrate

A high-quality AlN epitaxial film has been grown on a Si(111) substrate by metal–organic chemical vapor deposition through designing the AlN nucleation layer.