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Unlike traditional logic transistors, hot carrier degradation (HCD) in power transistors involves simultaneous and potentially correlated degradation in multiple regions. One must deconvolve and characterize the voltage- and temperature-dependence of these region-specific degradations to develop a predictive HCD model of power transistors. Unfortunately, power transistors' doping and geometrical complexities make it challenging to use traditional defect-profiling techniques, such as charge-pumping or gated-diode methods. This Letter uses a physics-based tandem-FET model of an Laterally Diffused MOS (LDMOS) transistor to develop a “three-point I–V spectroscopy” technique that uses the time-evolution of three critical points of the measured I–V characteristics to extract mobility and threshold voltage degradations in the channel and drift regions. This innovative approach should generalize to other configurations of the LDMOS transistor as well.

A β-Ga2O3 field effect transistor (FET) outperforms a GaN FET in Baliga's figure of merit (FOM) by 400% and Huang's chip area manufacturing figure of merit by 330%, suggesting that β-Ga2O3 could be a substrate of choice for next generation power transistors. However, its low thermal conductivity leads to extreme self-heating, which deteriorates the device performance during high voltage operation. A holistic evaluation of performance from a material-device-circuit perspective is necessary before reaching any conclusion regarding the technological viability of β-Ga2O3. In this paper, we develop a multiphysics and multiscale model for a material-device-circuit analysis of β-Ga2O3 FETs. The framework allows us to explore the effectiveness of various device design strategies (e.g., thermal shunts) for mitigating the thermal chokepoints and compare the performance of improved β-Ga2O3 FETs against that of GaN and SiC FETs. We highlight the limitations of traditional FOMs to analyze the relative performance of the new generation of power transistors whose structure incorporates stacked layers of materials with different thermal conductivities, like those of β-Ga2O3 FETs. We suggest device design strategies, such as wafer thinning, incorporation of heat shunts, and improved channel mobility, so that β-Ga2O3 FETs can compete commercially with GaN and SiC technologies.

In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m2, which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect result...

A simple surface modification process to reduce the negative influences of oxygen vacancies/surface contamination and promote the performance of ZnO ultraviolet (UV) sensor is reported. ZnO film was self-assembled by 3-aminopropyltrimethoxysilane (APTMS) molecules for passivating its surface defects. APTMS molecules are hydrolyzed at the methoxy end, and then condensed with the substrate hydroxyl groups to produce siloxanes. Compared with the conventional ZnO UV sensor, in which the reproducibility and homogeneity of device performance strongly suffer from a difficulty in controlling the ZnO surface state conditions, the APTMS molecules leads to a reduction of the dark leakage current by more than 2 orders of magnitude.

Al-doped ZnO (AZO) deposited by radio frequency co-sputtering is formed on epitaxial Mg-doped GaN template at room temperature to achieve n-AZO/p-GaN heterojunction. Alignment of AZO and GaN bands is investigated using synchrotron radiation based cross-sectional scanning photoelectron microscopy and spectroscopy on the nonpolar side-facet of a vertically c-axis aligned heterostructure. It shows type-II band configuration with valence band offset of 1.63 ± 0.1 eV and conduction band offset of 1.61 ± 0.1 eV, respectively. Rectification behavior is clearly observed, with a ratio of forward-to-reverse current up to six orders of magnitude when the bias is applied across the p-n junction.

In this study, a multi-color emission was observed from the large-area GaN-based photonic quasicrystal (PQC) nanopillar laser. The GaN PQC nanostructure was fabricated on an n-GaN layer by using nanoimprint lithographic technology. The regrown InGaN/GaN multiple quantum wells (MQWs) formed a nanopyramid structure on top of the PQC nanopillars. A lasing action was observed at ultraviolet wavelengths with a low threshold power density of 24 mJ/cm2, and a green color emission from InGaN/GaN MQWs was also achieved simultaneously.

We propose a lighting mechanism for generating uniform planar light. The device integrates electron beams induced by gas discharge with cathodoluminescence at the anode, where the spectra of the emitted light depend entirely on the phosphor materials coated on the anode. Consequently, ultraviolet is not required and the usage of mercury can be avoided. In addition, the features of double-side lighting, transparency, and gray-scale images indicate that the flat electron emission lamp might become potential candidate for the next generation green lighting source.