Matteo Meneghini

• PhD
• Professor (Associate) at University of Padua

This work reports on the control of the n‐GaN surface using a simple Mg diffusion process. It is shown that the Mg diffusion process enables a GaN surface without Fermi‐level pinning. The process results in the realization of n‐GaN unipolar camel diodes where increasing the metal work function leads to an incremental barrier height increase. Notabl...

We propose a detailed approach for modeling the C–V characteristic of complex heterostructure-based devices, investigating the case of UV-C LEDs. The study is based on combined experimental measurements and TCAD simulations, and explores: i) the impact of defects at critical interfaces on the apparent charge profile; ii) the dependence of the C–V c...

We evaluate the degradation of 1.3 µm InAs quantum-dot laser diodes epitaxially grown on silicon. For the first time, the optical degradation mechanisms are investigated by evaluating the variations in the gain spectra measured during a constant-current stress test. Remarkably, the gain spectra showed that the reduction in the peak modal gain is do...

Most photovoltaic (PV) modules are guaranteed for 25–30 years. However, severe climatic events, particularly hail, can lead premature damage. In this article, a residential PV system in Padova, Italy, was studied after exposure to a severe storm with hailstones up to 16 cm in diameter, which is more than two times larger than the standard size of t...

This paper reports on the degradation analysis of high-power light-emitting diodes (LEDs) for horticulture lighting applications. The study is based on the experimental characterization of state-of-the-art monochromatic commercial off-the-shelf LEDs from the same product-line and the same manufacturer. In this work we report the degradation kinetic...

Recently, the use of insulating substrates has emerged as a viable option for the fabrication of GaN power transistors exceeding 1 kV. Such structures are of interest because no doped buffer is used, so—ideally—a low dynamic R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> DSON </sub> is expected. Th...

The performance, stability, and reliability of GaN transistors are affected by charge trapping effects, thus calling for dependable characterization and modelling techniques for these phenomena. In this work, after a review of the different GaN deep levels and a description of the possible compact and TCAD physical modelling approaches that can be...

We analyzed the threshold-voltage dynamic instabilities induced by OFF-state stress in pseudo-vertical GaN-on-Si Trench MOSFETs (TMOS). Extensive measurements revealed that OFF-state stress experiments induce a progressive increase of threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"...

We demonstrate that exposure to positive gate bias can favor a fast recovery of the threshold voltage variation induced by off-state stress, in p-GaN gate high electron mobility transistors. Two process splits were investigated, having different Schottky barriers at the metal/p-GaN junction. Results indicate that: (a) drain stress may result in sig...

Advanced millimeter-wave (mm-wave) transceiver systems, including future mm-wave 5G and 6G mobile networks, are of great interest to support high-data-rate communications (e.g., 10 Gb/s or higher) and backhaul communications with >50 Gb/s. Since the E band and beyond can also support multigigahertz bandwidths, there is also growing interest in phas...

The mass production of photovoltaic (PV) devices requires fast and reliable characterization methods and equipment. PV manufacturers produce a complete module roughly every 20 s, and the electrical performance assessment is typically completed in less than 1 s. Times are even more stringent during cell manufacturing. To be competitive in the PV mar...

We investigate the degradation mechanisms of In0.2Ga0.8N/GaN light emitting diodes through combined experimental analysis and simulations. The devices were submitted to constant current stress at 100 mA. Depending on the measuring current level, two degradation trends were observed: at high test currents (e.g. 200 mA), a monotonic decrease in optic...

The study of deep-level defects in semiconductors has always played a strategic role in the development of electronic and optoelectronic devices. Deep levels have a strong impact on many of the device properties, including efficiency, stability, and reliability, because they can drive several physical processes. Despite the advancements in crystal...

We studied four AlGaN-based 265 nm LEDs with increasing QW thickness (1.4, 3, 6 and 9 nm) during a constant current stress at 100 A cm⁻². We focused our attention on the parasitic components of the emission spectra at low current levels and on the optical power recovery observed at high current levels. We associated every parasitic peak or band to...

In this paper we present an extensive analysis of the positive threshold voltage instability in Schottky p GaN gate enhancement-mode devices, investigated by a custom setup allowing an extended observation window, from the microsecond to hundreds of seconds. We show that a matrix of experiments can be specifically designed to investigate the voltag...

A precise measurement of optical power, forward voltage, and junction temperature of light-emitting diodes (LEDs) is the key for characterization and health monitoring of these devices. In many cases, LED characterization is carried out with relatively long (10 ms and longer) pulses, that is, in conditions in which self-heating can significantly im...

Gallium nitride (GaN) based high periodicity indium/GaN multiple quantum wells solar cells have recently been proposed for different applications: from operation in harsh environments, like space applications, to their use in concentrator solar harvesting system and wireless power transfer system. In this article, we extensively investigate the mec...

We present a comprehensive review and outlook of silicon carbide (SiC) and gallium nitride (GaN) transistors available on the market for current and next-generation power electronics. Material properties and structural differences among GaN and SiC devices are first discussed. Based on the analysis of different commercially available GaN and SiC po...

By combining microscopy investigation, light-beam induced current (LBIC), micro-photoluminescence ( $\mu $ -PL), and micro-electroluminescence ( $\mu $ -EL) characterization, we investigate the electrical and optical properties of V-pits and trench-like defects in high-periodicity InGaN/GaN multiple quantum wells (MQWs) solar cells. Experimental...

On behalf of myself and the other guest editors for the Special Issue on “Wide and Ultrawide Band Gap Semiconductor Devices for RF and Power Applications” featured in this month’s IEEE Transactions on Electron Devices, we are pleased to offer readers a selection of papers that span the contemporary landscape of wide and ultrawide bandgap semiconduc...

This article deals for the first time with the electrical degradation of novel 845 nm vertical-cavity silicon-integrated lasers (VCSILs) for silicon photonics (SiPh). We analyzed the reliability of these devices by submitting them to high current stress. The experimental results showed that stress induced: 1) a significant increase in the series re...

In this paper we investigate the reliability of AlGaN-based UV-C LEDs with an emission wavelength of 265 nm. By submitting the devices to constant current stress, two main electrical degradation processes are identified: a turn-on voltage shift and an increase in the forward leakage current. In particular, these processes were respectively attribut...

For the first time, we analyze the optical degradation of 1.3 mm InAs quantum dot laser diodes (QD LDs) epitaxially grown on silicon as a function of the number of dot-in-a-well layers (DWELLs). To this aim, we tested the reliability of two kinds of devices differing only in the number of DWELLs in the active region: QD LDs with three vs. five quan...

For the first time, we use electrical characterization, spectrally-resolved electroluminescence measurements and degradation tests to explain the negative activation energy of gate reliability in power GaN HEMTs with p-GaN Schottky gate. First, the origin of gate leakage current was modeled. The results indicate that the gate leakage current origin...

In this article, we investigate the optically induced degradation of Cu(InGa)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (CIGS) solar cells subjected to monochromatic laser irradiation. The devices under test are bifacial CIGS solar cells, fabricated on fluorine-doped SnO <sub xmlns:mml=...

Detrapping mechanisms and their dependence on applied bias have been studied in buffer-free AlGaN/GaN HEMTs on SiC. It is shown that the detrapping time constant decreases by orders of magnitude when the device is biased in semi-on conditions, or if the gate Schottky junction is forward biased with source and drain at ground. Despite completely dif...

Vertical GaN power MOSFET is a novel technology that offers great potential for power switching applications. Being still in an early development phase, vertical GaN devices are yet to be fully optimized and require careful studies to foster their development. In this work, we report on the physical insights into device performance improvements obt...

We discuss the degradation mechanisms of C-doped 0.15-μm gate AlGaN/GaN HEMTs tested by drain step-stress experiments. Experimental results show that these devices exhibit cumulative degradation effects during the step stress experiments in terms of either (i) transconductance (gm) decrease without any threshold-voltage (VT) change under OFF-state...

The kink effect in field-effect transistors (FETs) consists in a sudden increase in drain current, $\textit{I}_{\text{D}}$ , during a drain voltage sweep and leading to a higher $\textit{I}_{\text{D}}$ saturation value. We report new experimental data concerning the dynamic behavior of the “kink” in AlGaN/GaN HEMTs and correlate them with deep...

In the last years, the research on ultraviolet-C (UV-C) light emitting diodes (LEDs) focused its efforts on the solution of major problems that limited the emitted optical power (OP) and that caused the sudden failure of the devices. This led to the availability in the market of some devices with interesting electro-optical characteristics and prom...

In this work, for the first time, CdSe is applied as a buffer layer on thermally evaporated Sb2Se3-based solar cells on superstrate configuration. The influence of this buffer layer on the growth of Sb2Se3 and the performance of the finished devices have been analyzed and compared with the typical CdS/Sb2Se3 junction. Selenium vacancies in Sb2Se3...

Based on combined electrical analysis, microscopy investigation, and two-dimensional simulations we investigate the influence of V-pits on the turn- on voltage and current-voltage characteristics of high periodicity InGaN-GaN multiple quantum wells solar cells. Experimental measurements indicate that the sample with the thinnest p-GaN layer presen...

We present a detailed model of the static and dynamic gate leakage current in lateral β-Ga2O3 MOSFETs with an Al2O3 gate insulator, covering a wide temperature range. We demonstrate that (i) in the DC regime, current originates from Poole–Frenkel conduction (PFC) in forward bias at high-temperature, while (ii) at low temperature the conduction is d...

For the first time we investigate the optical degradation of vertical-cavity silicon-integrated lasers VCSILs) designed for operation at 845 nm in photonic integrated circuits (PICs). The study is based on the combined electro-optical characterization of VCSIL, submitted to constant-current stress tests at different current levels. The original res...

Recently, the introduction of a CdSe x Te 1-x (CST) buffer in the CdTe absorber has increased the photon absorption at both short wavelengths in the visible range (by removal of the parasitic absorption of the CdS layer) and at the infrared range (by reduction of the absorber band gap). But, moreover, the efficiency improvement is also attributed t...

Gallium nitride (GaN) multiple quantum well (MQW) solar cells proved to have very good performance in high-temperature conditions and under intense excitation. However, the long-term reliability under harsh conditions has not been investigated in the literature. The aim of this article is to fill this gap, by investigating the degradation mechanism...

DC characteristics of AlGaN/GaN HEMTs with different thickness values of the undoped GaN channel layer were compared. An abnormal transconductance ( $\textit{g}_{\textit{m}}\text{)}$ overshoot accompanied by a negative threshold voltage ( $\textit{V}_{\text{TH}}\text{)}$ shift was observed during $\textit{I}_{\text{DS}}$ – $\textit{V}_{\text{GS...

Herein, the reliability of commercial ultraviolet‐C (UV‐C) light‐emitting diodes (LEDs) subjected to constant current stress is reported. Electrical, optical, and spectral analyses are carried out on UV‐C LEDs with an emission peak of 275 nm and a nominal optical power of 12 mW at 100 mA. Degradation tests are carried out at the maximum rated curre...

The lifetime of deep-ultraviolet light-emitting diodes (LEDs) is still limited by a number of factors, which are mainly related to semiconductor defects, and still need to be clarified. This paper improves the understanding of UV LED degradation, by presenting an analysis based on combined deep-level transient spectroscopy (C-DLTS), electro-optical...

The long-term stability of ultraviolet (UV)-C light-emitting diodes (LEDs) is of major importance for many applications. To improve the understanding in this field, we analyzed the degradation of AlGaN-based UVC LEDs and modeled the variation of electrical characteristics by 2D simulations based on the results of deep-level optical spectroscopy (DL...

We investigate the impact of Mg-doping on the performance and degradation kinetics of AlGaN-based UV-C light-emitting diodes (LEDs). By comparing LEDs from three wafers with different nominal doping levels [Mg/(Al+Ga) ratio: 0.15%, 0.5%, and 1% in the gas phase during epitaxy] in the AlGaN:Mg electron-blocking layer (EBL), we demonstrate the follow...