As the key device in a UV warning system, a solid‐state UV photodetector has attracted great attention. Herein, a new UV photodetector structure based on vertical (Al, Ga)N nanowires with graphene electrode and Si substrate is designed and demonstrated. By graphene/vertical (Al, Ga)N nanowire array heterojunction, the rectifying characteristics of I–V curve are formed, and the dark current is 54 nA at −2 V bias. The fabricated device exhibits a responsivity of 0.176 mA W−1 at the bias of −2 V, as well as a stable switching characteristic. It is proposed that the photogenerated electrons and holes can reach positive and negative electrodes by diffusion or tunneling effect, even with thick AlN sections. This method can promote the implementation of low cost for UV photodetector with adjustable detection range nowadays.

In this paper, we report bidirectional negative differential resistance (NDR) in Al(Ga)N/GaN/AlN resonant tunneling diodes grown on free-standing GaN substrates by RF-plasma assisted molecular beam epitaxy. Bidirectional NDR has exhibited a current–voltage (I–V) characteristic in both forward and reverse biases at room temperature. The positive peak current density is 160 kA/cm2 with a peak to valley current ratio (PVCR) of 1.34, and the negative peak current density is 112 kA/cm2 with a high PVCR of 1.56. The bidirectional NDR is attributed to the change in the polarization field in the active region, which is caused by the asymmetric barrier component.

InGaN quantum dots (QDs) are promising candidates for GaN-based all-visible optoelectronic devices such as micro light-emitting diode and laser. In this study, self-assembled InGaN/GaN multi-quantum dots (MQDs) have been grown by plasma-assisted molecular beam epitaxy on c-plane GaN-on-sapphire template. A high density of over 3.8 × 1010 cm−2 is achieved and InGaN QDs exhibit a relatively uniform size distribution and good dispersity. Strong localization effect in as-grown InGaN QDs has been evidenced by temperature-dependent photoluminescence (PL). The variation of peak energy is as small as 35 meV with increasing temperature from 10 K to 300 K, implying excellent temperature stability of emission wavelength for InGaN MQDs. Moreover, the radiative and nonradiative recombination times were calculated by time-resolved PL (TRPL) measurements, and the temperature dependence of PL decay times reveal that radiative recombination dominates the recombination process due to the low dislocation density of QDs structure.