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In this article, we propose and investigate a GaN-based trench metal–insulator–semiconductor barrier Schottky rectifier with a beveled mesa and field plate (BM-TMBS). According to our study, the beveled mesa and field plate structures help to reduce the density of potential lines at the mesa corner and deplete the drift region in two-dimensional mode, respectively. By doing so, the electric field at the bottom corner of the trenches and Schottky contact/GaN interface can be decreased significantly and the breakdown voltage can also be improved remarkably when compared with the conventional TMBS rectifiers and the planar Schottky barrier diodes. Meanwhile, assisted by the beveled mesa structure, the improved current spreading effect and a better conductivity modulation can be obtained in the forward-conduction state. Our studies also show that the electric field profiles and charge-coupling effect can be influenced by the mesa angle, the insulating layer thickness (Tox), and the trench depth (Dtr). As a result, the optimized BM-TMBS rectifiers can obtain a high BV of ∼2 kV and a current density of ∼3 kA/cm2 at the forward bias of 2 V. [ABSTRACT FROM AUTHOR]

GaN‐based quasi‐vertical PIN diodes are grown on insulating sapphire substrates, and thus both the n‐electrode and the p‐electrode are made on the same side, which causes lateral current injection scheme. Therefore, one of the challenges for this design lies in the serious current crowding at the mesa edges, which leads to the local hole accumulation, and thus the Auger recombination significantly gives rise to the poor conductivity modulation in the drift region when the devices are forwardly biased. Herein, utilizing an embedded PN–GaN junction is proposed, such that the embedded PN–GaN junction is reversely biased when the PIN diode is in the on‐state condition. The built‐in electric field in the reversely biased PN–GaN junction depletes holes at the mesa edges, and correspondingly the Auger recombination can be decreased. The results also show that the proposed structures do not affect the breakdown voltage for PIN diodes. [ABSTRACT FROM AUTHOR]

In this work, we simply take advantage of the polarization effect to efficiently improve the hole injection from the p-type electron blocking layer (p-EBL) to the end of the active region for AlGaN based deep ultraviolet light emitting diodes (DUV LEDs). By properly increasing the AlN composition of AlGaN quantum barriers, a smaller positive polarized charge density at the last quantum barrier/p-EBL interface can be obtained, which correspondingly leads to the suppressed hole depletion and the reduced hole blocking effect in the p-EBL. Meanwhile, we properly increase the quantum well thickness so that the polarized electric field can even more accelerate the holes, and this will homogenize the hole distribution more across the MQWs. Therefore, the external quantum efficiency for DUV LEDs can be enhanced. [ABSTRACT FROM AUTHOR]

In this article, we have systematically investigated the impact of different structural parameters on the breakdown voltage for GaN-based trench MIS barrier-controlled Schottky (TMBS) rectifier. Compared with the planar Schottky rectifier, the TMBS rectifier has field plates on the mesa sidewalls so that the drift region can be depleted in a 2-D manner, which helps to decrease the electric field at the metal/mesa interface. However, the adoption of mesas can make the electric potential lines at the mesa corner dense and has large curvatures. Therefore, the premature breakdown can occur when the electric field therein reaches the critical condition. We find that the electric field profiles can be affected by insulation layer thickness, mesa width, trench depth, and different types of insulation layers. Then, we increase the breakdown voltage by homogenizing the electric field distribution in the mesa region, e.g., the electric field at mesa corners can be decreased by adopting properly thick sidewall insulator and small trench depth. Meanwhile, TMBS rectifier using sidewall insulating material with a large dielectric constant more favors a large breakdown voltage. [ABSTRACT FROM AUTHOR]

In this report, a parametric investigation on the n+-GaN/AlGaN/p+-GaN tunnel junction is made for III-nitride based ultraviolet light emitting diodes (UV LEDs). It is found that, on one hand, by using various Al compositions and AlGaN layer thicknesses, the n+-GaN/AlGaN/p+-GaN tunnel junction can modify the electric field therein, which will affect the carrier tunneling probability and the current-voltage characteristics. On the other hand, the Al composition and the AlGaN layer thickness also have a strong impact on the tunnel region width, which will affect the current flowing path and then influence the hole distribution apart from the p-type ohmic contact. This work conducts a comprehensive analysis and presents an in-depth understanding regarding the n+-GaN/AlGaN/p+-GaN tunnel junction, so that the hole concentration and the internal quantum efficiency can be significantly improved for III-nitride UV LEDs. [ABSTRACT FROM AUTHOR]

This study proposes to increase the breakdown voltage for GaN‐based PIN diodes using the polarization effect, such that a thin AlGaN layer is inserted into the drift layer to modulate the electric field profiles, and by properly designing the device architecture, the electric field in the drift layer can be remarkably reduced by the polarization effect, and this enables the enhancement of the breakdown voltage. The study further investigates the parametric sensitivity of the breakdown voltage for the proposed GaN‐based PIN diodes to different device structures with various drift layer thicknesses. Moreover, it is found that the position of the inserted AlGaN thin layer is also important in affecting the breakdown voltage, such that the AlGaN insertion layer reduces the electric field with the maximum intensity in the drift layer. [ABSTRACT FROM AUTHOR]

Electron overflow is one of the key factors that limit the quantum efficiency for AlGaN-based deep-ultraviolet light-emitting diodes. In this work, we report a numerical study to improve the electron injection efficiency by manipulating the electric field profiles via doping the n-Al0.60Ga0.40N electron source layer with different concentrations and reveal the physical mechanism of the Si doping effect on the electron and the hole injection. By utilizing the appropriate doping concentration, the electric field will reduce the electron drift velocity and, thus, the mean free path. Therefore, a higher electron capture efficiency by the multiple quantum wells (MQWs) and an increase of the hole concentration in the active region can be realized, resulting in an improved radiative recombination rate and an optical output power. [ABSTRACT FROM AUTHOR]

In this work, we propose to insert an In 0.07 Ga 0.93 N layer into the GaN quantum barriers for InGaN/GaN green light-emitting diodes (LEDs) to achieve the enhanced hole injection and improve the internal quantum efficiency (IQE). Nevertheless, we also find that the insertion layer cannot be too thin, and a properly thick insertion layer is recommended, because the polarization induced electric field in the GaN/In 0.07 Ga 0.93 N/GaN quantum barriers can accelerate holes, and thereby the hole blocking effect at the GaN/In 0.07 Ga 0.93 N interfaces and the increase for the valence band barrier height of p-EBL will be less significant. Other advantage is that the insertion In 0.07 Ga 0.93 N layer can also reduce the polarization induced electric field in the quantum wells, which is helpful to increase the radiative recombination rate. • GaN-InGaN-GaN barriers can improve hole injection by accelerating holes. • GaN-InGaN-GaN barriers can suppress QCSE. • GaN-InGaN-GaN barriers can improve the IQE of InGaN/GaN green light-emitting diodes. [ABSTRACT FROM AUTHOR]