Hsin-Hung Yao

King Abdullah University of Science and Technology

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Xiaohang Li

King Abdullah University of Science and Technology

Yi Lu

King Abdullah University of Science and Technology

Junxi Wang

Institute of Semiconductors

Che‐Hao Liao

King Abdullah University of Science and Technology

Jinmin Li

Chongqing Normal University

Michael Lehmann

Technische Universität Berlin

Jiangnan Dai

Wuhan National Laboratory for Optoelectronics

Tien‐Chang Lu

National Yang Ming Chiao Tung University

Michael Narodovitch

Technische Universität Berlin

J.H. Yan

National Cheng Kung University

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Technische Universität Berlin

Chinese Academy of Sciences

Georgia Institute of Technology

King Abdullah University of Science and Technology

University of Chinese Academy of Sciences

Ferdinand-Braun-Institut

Institute of Semiconductors

National Yang Ming Chiao Tung University

Brandenburg University of Technology Cottbus-Senftenberg

Huazhong University of Science and Technology

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Precise determination of polarization fields in c-plane GaN/Al_xGa_1-xN/GaN heterostructures with capacitance–voltage-measurements

Japanese Journal of Applied Physics (2019)

Norman Susilo Marcel Schilling Michael Narodovitch Hsin-Hung Yao Xiaohang Li

Due to changes in the spontaneous and piezoelectric polarization, AlGaN/GaN heterostructures exhibit strong polarization fields at heterointerfaces. For quantum wells, the polarization fields lead to a strong band bending and a redshift of the emission wavelength, known as quantum-confined Stark effect. In this paper the polarization fields of thin AlGaN layers in a GaN matrix were determined by evaluating the changes in the depletion region width in comparison to a reference sample without heterostructure using capacitance–voltage-measurements. The polarization fields for Al0.09Ga0.91N (0.6 ± 0.7 MV cm−1), Al0.26Ga0.74N (2.3 ± 0.6 MV cm−1), Al0.34Ga0.66N (3.1 ± 0.6 MV cm−1), Al0.41Ga0.59N (4.0 ± 0.7 MV cm−1) and Al0.47Ga0.53N (5.0 ± 0.8 MV cm−1) heterostructures were determined. The results of the field strength and field direction of all samples are in excellent agreement with values predicted by theory and a capacitance–voltage based Poisson-carrier transport simulation approach giving experimental evidence for a nonlinear increasing polarization field with Al-concentration.

Band bending

Wide-bandgap semiconductor

10.7567/1347-4065/ab09dd

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Citations (3)

AlN/[beta]-Ga2O3-based HEMT for high-power devices (Conference Presentation)

Yi Lu Hsin-Hung Yao Xiaohang Li

In this work, the heterostructures of III-N materials/β-Ga2O3 based on the modern polarization theory and band alignment are systematically investigated. The nitrogen (N)-polar AlN/β-Ga2O3 heterojunction is found that can form the triangle channel and hold large 2DEG density on the interface through polarization engineering. Compared with GaN-based HEMT, the proposed N-polar AlN/β-Ga2O3 HEMT with polarization-induced property can realize much larger 2DEG density, better DC and transconductance performance, as well as higher breakdown voltage.

Transconductance

Wide-bandgap semiconductor

10.1117/12.2545370

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Polarization matched c-plane III-nitride quantum well structure

Hsin-Hung Yao Yi Lu Kuang‐Hui Li Feras AlQatari Che‐Hao Liao

Polarization-matched quantum wells (QWs) can lead to maximized electron-hole wave functions overlap and low efficiency droop at high current density. By using the modern theory of polarization with hexagonal reference, c-plane InAlN/InGaN QWs were explored and designed for polarization matching. The simulation results show that, even on c-plane, polarization-matched structures can be achieved by adjusting strain and material composition. The In composition of larger than 35% of InAlN was required to match the total polarization of InGaN at any given composition. Considering the bandgap's bowing factors of III-nitride ternary alloys, In_0~0.1Ga_1.0-0.9N as quantum barrier (QB) provided enough potential barriers for In_0.35~0.45Al_0.65-0.55N to form a multiple QW (MQW) structure. The results indicated that improper resistance of MQW and the existing fixed charge between the interfaces of p-type region/MQW and n-type region/MQW could result in nonuniform carrier distributions and current leakage, respectively. Furthermore, we found that In_0.41Al_0.59N/In_0.1Ga_0.9N polarization-matched MQW had proper resistance; however, such structure produced a huge polarization fixed-charge between the junction interface. By studying the strain level of InAlN QW and GaN QB, which can be grown on AlN/GaN superlattice templates, the In_0.33Al_0.67N/GaN polarization-matched MQW structure has been specifically designed with small resistance and without inducing improper polarization fixed charge. By optimizing the number and thickness of QWs, the 425nm LED has relative IQE of 56% and efficiency droop of only 7% at high current density of 333 A/cm². This study provides guidance for development of In-rich InAlN materials.

10.1117/12.2509873

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AlN/beta-Ga2O3 based HEMT: a potential pathway to ultimate high power device

arXiv (Cornell University) (2019)

Yi Lu Hsin-Hung Yao Jingtao Li J.H. Yan Junxi Wang

Gallium Oxide (Ga2O3) has a huge potential on the power device for its high breakdown filed and good transport properties. beta-Ga2O3 as the thermodynamics stable phase, has been demonstrated to form high electron mobility transistor (HEMT) through delta-doping in the barrier due to its none-polar property. Following the development in III-V HEMT which turns from delta-doping-induced to polarization-induced 2DEG, an alternative method based on III-N materials/beta-Ga2O3 heterostructure is proposed that utilizing the polarization difference on the interface. Further requirements of electric field and conduction band difference show that only nitrogen (N)-polar AlN on beta-Ga2O3 can form the channel and hold large 2DEG concentration on the interface. Compared with conventional metal-polar AlN/GaN HEMT, the proposed N-polar AlN/beta-Ga2O3 HEMT show a much larger 2DEG concentration, the spontaneous-polarization-dominated electric field, better DC output performance, as well as higher breakdown voltage. This study provides a new research approach that shifting from delta-doping-induced to polarization-induced on beta-Ga2O3-based HEMT, which can also be a guideline for community excavating the application potential of Ga2O3.

BETA (programming language)

10.48550/arxiv.1901.05111

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III-Nitride Deep UV LED Without Electron Blocking Layer

IEEE photonics journal (2019)

Zhongjie Ren Yi Lu Hsin-Hung Yao Haiding Sun Che‐Hao Liao

AlGaN-based deep UV (DUV) LEDs generally employ a p-type electron blocking layer (EBL) to suppress electron overflow. However, Al-rich III-nitride EBL can result in challenging p-doping and large valence band barrier for hole injection as well as epitaxial complexity. As a result, wall plug efficiency (WPE) can be compromised. Our systematic studies of band diagram and carrier concentration reveal that carrier concentrations in the quantum well and electron overflow can be significantly impacted because of the slope variation of the quantum barrier (QB) conduction and valence bands, which in turn influence radiative recombination and optical output power. Remarkably, grading the Al composition from 0.60 to 0.70 for the 12-nm-thick AlGaN QB of the DUV LED without the EBL can lead to 13.5% higher output power and similar level of overflown electron concentration (~1 × 10 ¹⁵ /cm ³ ) as opposed to the conventional DUV LED with the p-type EBL. This paradigm is significant for the pursuit of higher WPE or shorter emission wavelength for DUV LEDs and lasers, as it provides a new direction for addressing electron overflow and hole injection issues.

Quantum Efficiency

10.1109/jphot.2019.2902125

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Citations (40)

Strong Ultraviolet Emission from InGaN/AlGaN Multi Quantum Well Grown by Multi-step Process

Extended Abstracts of the 2020 International Conference on Solid State Devices and Materials (2006)

Hou-Guang Chen Hsin-Hung Yao Jung-Tang Chu Nai-Fang Hsu Tien‐Chang Lu

Ultraviolet

Wide-bandgap semiconductor

10.7567/ssdm.2006.i-2-6

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