Gallium Oxide has undergone rapid technological maturation over the last decade, pushing it to the forefront of ultra-wide band gap semiconductor technologies. Maximizing the potential for a new semiconductor system requires a concerted effort by the community to address technical barriers which limit performance. Due to the favorable intrinsic material properties of gallium oxide, namely, critical field strength, widely tunable conductivity, mobility, and melt-based bulk growth, the major targeted application space is power electronics where high performance is expected at low cost. This Roadmap presents the current state-of-the-art and future challenges in 15 different topics identified by a large number of people active within the gallium oxide research community. Addressing these challenges will enhance the state-of-the-art device performance and allow us to design efficient, high-power, commercially scalable microelectronic systems using the newest semiconductor platform.
The results of a detailed investigation of electrically active defects in metal-organic chemical vapor deposition (MOCVD)-grown β-Ga2O3 (010) epitaxial layers are described. A combination of deep level optical spectroscopy (DLOS), deep level transient (thermal) spectroscopy (DLTS), and admittance spectroscopy (AS) is used to quantitatively map the energy levels, cross sections, and concentrations of traps across the entire ∼4.8 eV bandgap. States are observed at EC-0.12 eV by AS; at EC-0.4 eV by DLTS; and at EC-1.2 eV, EC-2.0 eV, and EC-4.4 eV by DLOS. While each of these states have been reported for β-Ga2O3 grown by molecular-beam epitaxy (MBE) and edge-defined film fed grown (EFG), with the exception of the EC-0.4 eV trap, there is both a significantly different distribution in the concentration of these states and an overall ∼10× reduction in the total trap concentration. This reduction is consistent with the high mobility and low background compensating acceptor concentrations that have been reported for MOCVD-grown (010) β-Ga2O3. Here, it is observed that the EC-0.12 eV state dominates the overall trap concentration, in marked contrast with prior studies of EFG and MBE material where the state at EC-4.4 eV has dominated the trap spectrum. This sheds light on possible physical sources for this ubiquitous DLOS feature in β-Ga2O3. The substantial reduction in trap concentration for MOCVD material implies great promise for future high performance MOCVD-grown β-Ga2O3 devices.
In(Ga)As/GaAs-based quantum dot infrared photodetectors (QDIPs) have emerged as one of the most suitable devices for infrared detection. However, quantum dot devices suffer from lower efficiencies due to a low fill-factor (∼20%–25%) of dots. Here, we report a post-growth technique for improving the QDIP performance using low energy light ion (H−) implantation. At high bias, there is evidence of suppression in the field-assisted tunneling component of the dark current. Enhancement in peak detectivity (D*), a measure of the signal-to-noise ratio, by more than one order, from ∼109 to 2.44 × 1010 cm Hz1/2/W was obtained from the implanted devices.
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