Jr-Hau He

Dr. Jr-Hau He

Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
25 July 2014 in ACS Nano
Verified
Journal Article
Closed access
MTMeng-Lin Tsai
Meng-Lin Tsai
SSSheng-Han Su
Sheng-Han Su
JCJan-Kai Chang
Jan-Kai Chang
DTDung-Sheng Tsai
Dung-Sheng Tsai
CCChang-Hsiao Chen
Chang-Hsiao Chen
JHJr-Hau He
Jr-Hau He

31 July 2015 in Science
Verified
Journal Article
Closed access
PDF file
MLMing-Yang Li
Ming-Yang Li
Yumeng ShiYumeng Shi
Yumeng Shi
CCChia-Chin Cheng
Chia-Chin Cheng
LLLi-Syuan Lu
Li-Syuan Lu
YLYung-Chang Lin
Yung-Chang Lin
LLLain-Jong Li
Lain-Jong Li
Electronic junctions on edge: Two-dimensional materials such as graphene are attractive materials for making smaller transistors because they are inherently nanoscale and can carry high currents. However, graphene has no band gap and the transistors are “leaky”; that is, they are hard to turn off. Related transition metal dichalcogenides (TMDCs) such as molybdenum sulfide have band gaps. Transistors based on these materials can have high ratios of “on” to “off” currents. However, it is often difficult to make a good voltage-biased (p-n) junction between different TMDC materials. Li et al. succeeded in making p-n heterojunctions between two of these materials, molybdenum sulfide and tungsten selenide. They did this not by stacking the layers, which make a weak junction, but by growing molybdenum sulfide on the edge of a triangle of tungsten selenide with an atomically sharp boundary Science , this issue p. 524

23 January 2014 in Scientific Reports
Verified
Journal Article
Open access
PDF file
WZWenjing Zhang
Wenjing Zhang
CCChih-Piao Chuu
Chih-Piao Chuu
JHJing-Kai Huang
Jing-Kai Huang
CCChang-Hsiao Chen
Chang-Hsiao Chen
MTMeng-Lin Tsai
Meng-Lin Tsai
LLLain-Jong Li
Lain-Jong Li
Due to its high carrier mobility, broadband absorption, and fast response time, the semi-metallic graphene is attractive for optoelectronics. Another two-dimensional semiconducting material molybdenum disulfide (MoS2) is also known as light- sensitive. Here we show that a large-area and continuous MoS2 monolayer is achievable using a CVD method and graphene is transferable onto MoS2. We demonstrate that a photodetector based on the graphene/MoS2 heterostructure is able to provide a high photogain greater than 108. Our experiments show that the electron-hole pairs are produced in the MoS2 layer after light absorption and subsequently separated across the layers. Contradictory to the expectation based on the conventional built-in electric field model for metal-semiconductor contacts, photoelectrons are injected into the graphene layer rather than trapped in MoS2 due to the presence of a perpendicular effective electric field caused by the combination of the built-in electric field, the applied electrostatic field, and charged impurities or adsorbates, resulting in a tuneable photoresponsivity.

16 April 2013 in ACS Nano
Verified
Journal Article
Closed access
DTDung-Sheng Tsai
Dung-Sheng Tsai
KLKeng-Ku Liu
Keng-Ku Liu
DLDer-Hsien Lien
Der-Hsien Lien
MTMeng-Lin Tsai
Meng-Lin Tsai
CKChen-Fang Kang
Chen-Fang Kang
JHJr-Hau He
Jr-Hau He

11 May 2020 in Light: Science & Applications
Verified
Journal Article
Open access
PDF file
ZLZhaojun Liu
Zhaojun Liu
CLChun-Ho Lin
Chun-Ho Lin
BHByung-Ryool Hyun
Byung-Ryool Hyun
CSChin-Wei Sher
Chin-Wei Sher
ZLZhijian Lv
Zhijian Lv
JHJr-Hau He
Jr-Hau He
Micro-light-emitting diodes (μ-LEDs) are regarded as the cornerstone of next-generation display technology to meet the personalised demands of advanced applications, such as mobile phones, wearable watches, virtual/augmented reality, micro-projectors and ultrahigh-definition TVs. However, as the LED chip size shrinks to below 20 μm, conventional phosphor colour conversion cannot present sufficient luminance and yield to support high-resolution displays due to the low absorption cross-section. The emergence of quantum dot (QD) materials is expected to fill this gap due to their remarkable photoluminescence, narrow bandwidth emission, colour tuneability, high quantum yield and nanoscale size, providing a powerful full-colour solution for μ-LED displays. Here, we comprehensively review the latest progress concerning the implementation of μ-LEDs and QDs in display technology, including μ-LED design and fabrication, large-scale μ-LED transfer and QD full-colour strategy. Outlooks on QD stability, patterning and deposition and challenges of μ-LED displays are also provided. Finally, we discuss the advanced applications of QD-based μ-LED displays, showing the bright future of this technology.

17 October 2019 in Advanced Materials
Verified
Journal Article
Closed access
PDF file
VRVinoth Ramalingam
Vinoth Ramalingam
PVPurushothaman Varadhan
Purushothaman Varadhan
HFHui‐Chun Fu
Hui‐Chun Fu
HKHyunho Kim
Hyunho Kim
DZDaliang Zhang
Daliang Zhang
JHJr-Hau He
Jr-Hau He