Browsing by Author "Ao, Jin-Ping"

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AlGaN/GaN high electron mobility transistors with a low sub-threshold swing on free-standing GaN wafer
(2017-09-01)
Liu, Xinke
;
Gu, Hong
;
Li, Kuilong
;
Guo, Lunchun
;
Zhu, Deliang
This paper reported AlGaN/GaN high electron mobility transistors (HEMTs) with low sub-threshold swing SS on free-standing GaN wafer. High quality AlGaN/GaN epi-layer has been grown by metal-organic chemical vapor deposition (MOCVD) on free-standing GaN, small full-width hall maximum (FWHM) of 42.9 arcsec for (0002) GaN XRD peaks and ultralow dislocation density (similar to 10(4)-10(5) cm(-2)) were obtained. Due to these extremely high quality material properties, the fabricated AlGaN/GaN HEMTs achieve a low SS (similar to 60 mV/decade), low hysteresis of 54 mV, and high peak electron mobility mu(eff) of similar to 1456 cm(2)V(-1)s(-1). Systematic study of materials properties and device characteristics exhibits that GaN-on-GaN AlGaN/GaNHEMTsare promising candidate for next generation high power device applications. (C) 2017 Author(s).
GaN Schottky Barrier Diodes on Free-Standing GaN Wafer
(2017-01-01)
Liu, Xinke
;
Gu, Hong
;
Li, Kuilong
;
Wang, Jianfeng
;
Wang, Lei
In this paper, vertical GaN Schottky barrier diodes (SBDs) have been demonstrated on the freestanding (FS) GaN wafer. Room temperature photoluminescence shows no emission of yellow luminescence, due to the eliminating the point defects (O-N, V-Ga). The average full width half maximum (FWHM) value of.-scans for (0001) and (10-12) planes is 53 and 103 arcsec, respectively, as measured by high resolution X-ray diffraction; the average dislocation density at the top surface measured by cathodoluminescence is similar to 7.7 x 10(5) cm(-2). The vertical GaN SBDs fabricated on this FS-GaN wafer achieve a breakdown voltage of 1200 V, an on-state resistance R-on of 7 m Omega.cm(2), and a current on/off ratio I-on/I-off of similar to 2.3 x 10(10), which leads to a power device figure-of-merit V-BR(2)/R-on of 2.1 x 10(8) V-2 Omega(-1) cm(-2). TCAD simulation was employed to study the device breakdown mechanism, and shows the breakdown mechanism is due to the impact ionization at the edge of the Schottky gate. (c) 2017 The Electrochemical Society. All rights reserved.
Large-Scale Transparent Molybdenum Disulfide Plasmonic Photodetector Using Split Bull Eye Structure
(2018-10-18)
Sourav, Adhikary
;
Li, Zhiwen
;
Huang, Zhonghui
;
Botcha, Venkata Divakar
;
Hu, Cong
A high performance photodetector array on transparent substrate is highly sought after for enabling next-generation imaging technology at the visible wavelengths. 2D materials such as molybdenum disulfide (MoS2) are attractive for such application owing to its superior optoelectronic properties and transparency when scaled to atomic thinness. Here, direct growth of MoS2 on centimeter-scale transparent Al2O3 substrate is reported using a high yield and scalable chemical vapor deposition approach. This enables a large area photodetector array to be demonstrated, wherein aluminum split bull eye (SBE) plasmonic structure is integrated to achieve further performance boost due to surface plasmon resonance (SPR) effect. For a wavelength of 405 nm, the plasmonic MoS2 detector achieves an ultralow noise equivalent power of approximate to 6.2 x 10-14 W Hz(-1/2) and a high responsivity of 7.26 A W-1 at a small bias of 1.0 V, which is more than 6x larger than the reference detector due to SPR effect. Finite-difference time-domain simulation confirms a higher concentration of optical field distribution at the center of the SBE structure, which is responsible for the enhancement of photocurrent and sensitivity even at low-light condition.