We propose an innovative ultrathin AlGaN/InAlN heterojunction (HJ) inserted in AlGaN-based deep ultraviolet light-emitting diode (DUV LED) structure. Theoretical investigations indicate that the AlGaN/InAlN HJ is quite beneficial to suppress electron leakage and improve hole injection. These boosted characteristics strengthen the radiative recombination in the active region leading to remarkably improved optical power. Carrier transfer analysis reveals that the InAlN layer enhances the tunneling process for holes. The distinct AlGaN/InAlN HJ provides a promising alternative to be applied in DUV LED structures, as it not only functions as a sufficient electron blocker, but substantially facilitates the hole transport.

A nearly lattice-matched In0.12Al0.88N/Al0.21Ga0.79N heterostructure field-effect transistor (HFET) was fabricated and its device characteristics were evaluated. The fabricated device showed good pinch-off characteristics with a high breakdown field of 118 V/μm. A simple device calculation based on the experimental results showed the possibility that a low specific on-resistance below those of conventional AlGaN-channel HFETs can be achieved for InAlN/AlGaN HFETs in the case where a specific contact resistivity is less than 1 × 10−5 Ω cm2.

We demonstrate high-performance ultraviolet photodetectors (UV-PDs) based on lattice-matched (LM) InAlN/AlGaN heterostructure field-effect transistors (HFETs) gated by transparent ITO films. Low dark currents of 6.8 × 10−8 and 6.1 × 10−7 A/mm and high photocurrent gains over four and three orders of magnitude were obtained for the LM In0.12Al0.88N/Al0.21Ga0.79N and In0.10Al0.90N/Al0.34Ga0.66N HFETs, respectively. The negative threshold voltage shifts under illumination indicate that most of the photo-generated carriers are transported in the two-dimensional gas (2DEG) region around the InAlN/AlGaN interface. High peak responsivities of 2.2 × 104 and 5.4 × 104 A/W and large UV-to-visible rejection ratios greater than 104 and 103 were achieved for the LM In0.12Al0.88N/Al0.21Ga0.79N and In0.10Al0.90N/Al0.34Ga0.66N HFET-type UV-PDs, respectively. These improved performances with respect to other AlGaN UV-PDs around the same wavelength detection range may possibly be attributed to the greater contribution of the photogenerated electrons to the 2DEG, which results from the increase in the polarization sheet charge density at the InAlN/AlGaN interface. The LM InAlN/AlGaN heterostructures provide relatively promising candidates for realizing high-performance HFET-type UV-PDs.

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A 6H-SiC substrate with femtosecond-laser-induced periodic nanostructures was used as an underlayer for GaN growth. GaN nuclei were formed on the periodic nanostructure selectively. The in-plane direction of GaN was dependent on the in-plane direction of the SiC substrate, and no dependent on the direction of the periodic nanostructures or laser scanning. We suggest that the fine structure and high wettability at the region of the periodic nanostructure enhanced the adsorption of GaN nuclei preferentially. This technique will enable selective growth without masks or solution exposure.