Atomic-Monolayer Two-Dimensional Lateral Quasi-Heterojunction Bipolar Transistors with Resonant Tunneling Phenomenon

TL;DR: The experimental observation of quasi-heterojunction bipolar transistors utilizing a monolayer of the lateral WSe2-MoS2 junctions as the conducting p-n channel is demonstrated, and the negative differential resistance in the electrical characteristics is observed.

Abstract: High-frequency operation with ultrathin, lightweight, and extremely flexible semiconducting electronics is highly desirable for the development of mobile devices, wearable electronic systems, and defense technologies. In this work, the experimental observation of quasi-heterojunction bipolar transistors utilizing a monolayer of the lateral WSe2–MoS2 junctions as the conducting p–n channel is demonstrated. Both lateral n–p–n and p–n–p heterojunction bipolar transistors are fabricated to exhibit the output characteristics and current gain. A maximum common-emitter current gain of around 3 is obtained in our prototype two-dimensional quasi-heterojunction bipolar transistors. Interestingly, we also observe the negative differential resistance in the electrical characteristics. A potential mechanism is that the negative differential resistance is induced by resonant tunneling phenomenon due to the formation of quantum well under applying high bias voltages. Our results open the door to two-dimensional material...

Summary

Introduction

• “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record.
• The heterojunction bipolar transistor (HBT) is very similar to the BJT, but uses different semiconductor materials with different bandgaps for the emitter and base regions instead.

RESULTS AND DISCUSSION

• For the synthesis of WSe2-MoS2 lateral heterostructure, a monolayer MoS2 was grown using chemical vapor deposition (CVD) on top of sapphire substrates.
• Fig. 1 shows the characterization of the lateral WSe2-MoS2 heterostructure in one of the ribbons.
• Fig. 4(c) shows the common-emitter output characteristics of the lateral n-p-n quasi-heterojunction bipolar transistor.
• Once the energy in the emitter region is higher than the energy in the quantum well (base region), the authors can observe the resonant tunneling behavior.
• In addition, the authors also note that when the VBE is increased at relatively large bias, the current of the collector would not increase like common bipolar junction transistors.

CONCLUSION

• The authors have demonstrated quasi-heterojunction bipolar transistors using a monolayer of the lateral heterojunction transition metal dichalcogenide materials, namely WSe2-MoS2.
• Two types of the lateral quasiheterojunction bipolar transistor, n-p-n and p-n-p, are meticulously fabricated and studied in the same piece of a flake in order to compare the device performance between them.
• Furthermore, the authors also observe that the negative differential resistance (NDR) in their devices.
• The NDR behavior is caused by resonant tunneling phenomenon due to the formation of quantum well under applying high bias voltages in the base region and collector region.

Full text

Atomic-Monolayer Two-Dimensional Lateral
Quasi-Heterojunction Bipolar Transistors
with Resonant Tunneling Phenomenon
Item Type Article
Authors Lin, Che-Yu; Zhu, Xiaodan; Tsai, Shin-Hung; Tsai, Shiao-Po; Lei,
Sidong; Li, Ming-yang; Shi, Yumeng; Li, Lain-Jong; Huang, Shyh-
Jer; Wu, Wen-Fa; Yeh, Wen-Kuan; Su, Yan-Kuin; Wang, Kang L.;
Lan, Yann-Wen
Citation Lin C-Y, Zhu X, Tsai S-H, Tsai S-P, Lei S, et al. (2017) Atomic-
Monolayer Two-Dimensional Lateral Quasi-Heterojunction
Bipolar Transistors with Resonant Tunneling Phenomenon. ACS
Nano. Available: http://dx.doi.org/10.1021/acsnano.7b05012.
Eprint version Post-print
DOI 10.1021/acsnano.7b05012
Publisher American Chemical Society (ACS)
Journal ACS Nano
Rights This document is the Accepted Manuscript version of a Published
Work that appeared in final form in ACS Nano, copyright ©
American Chemical Society after peer review and technical
editing by the publisher. To access the final edited and published
work see http://pubs.acs.org/doi/abs/10.1021/acsnano.7b05012.
Download date 09/08/2022 20:45:32
Link to Item http://hdl.handle.net/10754/625850

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Article
Atomic-Monolayer Two-Dimensional Lateral Quasi-Heterojunction
Bipolar Transistors with Resonant Tunneling Phenomenon
Che-Yu Lin, Xiaodan Zhu, Shin-Hung Tsai, Shiao-Po Tsai, Sidong Lei, Ming-Yang Li, Yumeng Shi, Lain-
Jong Li, Shyh-Jer Huang, Wen-Fa Wu, Wen-Kuan Yeh, Yan-Kuin Su, Kang L. Wang, and Yann-Wen Lan
ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.7b05012 • Publication Date (Web): 04 Oct 2017
Downloaded from http://pubs.acs.org on October 10, 2017
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1
Atomic-Monolayer Two-Dimensional Lateral Quasi-
Heterojunction Bipolar Transistors with Resonant Tunneling
Phenomenon
Che-Yu Lin
1
,Xiaodan Zhu
2
,Shin-Hung Tsai
2
,Shiao-Po Tsai
2
,Sidong Lei
2
,Ming-Yang Li
3
,Yumeng Shi
4
,
Lain-Jong Li
5
,Shyh-Jer Huang
6
,Wen-Fa Wu
7
,Wen-Kuan Yeh
7
, Yan-Kuin Su
1,8
,
Kang L.Wang
2
,Yann-Wen Lan
9,*
1
Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung
University, Tainan 701, Taiwan.
2
Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California,
United States.
3
Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan.
4
SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, Shenzhen University,
Shenzhen 518060, China
5
Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST),
Thuwal, Kingdom of Saudi Arabia.
6
Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan.
7
National Nano Device Laboratories, National Applied Research Laboratories, Hsinchu 30078, Taiwan.
8
Department of Electrical Engineering, Kun Shan University, Tainan 710, Taiwan.
9
Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan
Tel: +886-2-77346094, Fax: +886-2-29326408, Email: ywlanblue@gmail.com; ywlan@ntnu.edu.tw
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2
Abstract
—
High-frequency operation with ultra-thin, lightweight and extremely flexible semiconducting
electronics are highly desirable for the development of mobile devices, wearable electronic systems and defense
technologies. In this work, the experimental observation of quasi-heterojunction bipolar transistors utilizing a
monolayer of the lateral WSe
2
-MoS
2
junctions as the conducting p-n channel is demonstrated. Both lateral n-p-
n and p-n-p heterojunction bipolar transistors are fabricated to exhibit the output characteristics and current
gain. A maximum common-emitter current gain of around 3 is obtained in our prototype two-dimensional
quasi-heterojunction bipolar transistors. Interestingly, we also observe the negative differential resistance in the
electrical characteristics. A potential mechanism is that the negative differential resistance is induced by
resonant tunneling phenomenon due to the formation of quantum well under applying high bias voltages. Our
results open the door to two-dimensional materials for high-frequency, high-speed, high-density and flexible
electronics.
Keywords: 2D materials, heterojunction bipolar transistors, resonant tunneling phenomenon, lateral junction,
atomic layered,
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3
One of the major transistors is bipolar junction transistor (BJT) that is formed by connecting two opposite
junction diodes and utilizes both electron and hole charge carriers. It is a three-terminal device represented
separately by emitter、base and collector, and is a critical component in many analog, digital, and sensor
applications. BJTs are manufactured in two types, NPN and PNP, and the two complementary configuration
transistors could be fabricated in the same circuit which could make the circuit design more flexible. The
amplification of current is the basic function of a BJT.
1
This allows BJTs to be used as amplifiers or switches,
giving them wide applicability in consumer electronics, examples of applications including communication
products, computers, audio-visual and sound equipment, and various instruments. The heterojunction bipolar
transistor (HBT) is very similar to the BJT, but uses different semiconductor materials with different bandgaps
for the emitter and base regions instead.
2,3
Compared to BJT, HBT can be operated at very high frequencies, up
to several hundred GHz. It is commonly used in radio-frequency (RF) systems such as RF power amplifiers in
cellular phones.
4,5
Traditional materials used for epitaxial layers of HBT include silicon/silicon-germanium
alloys,
6
aluminum gallium arsenide/gallium arsenide, and indium phosphide/indium gallium arsenide.
The advent of atomically thin two-dimensional (2D) crystals has sparked a paradigm shift in
nanotechnology.
7,8
Since the last decade, we are capable of truly exploring and implementing device concepts at
the ultimate physical thickness limit in addition to having at our disposal a myriad of 2D materials, each of
which exhibits distinctive electronic and optical properties.
9
There exist many 2D materials with energy
bandgaps in the range between 1 and 2 eV. By carefully mixing and matching materials with different bandgap
values, it can provide the potential barriers needed to limit the injection of holes from the base into the emitter
region and thus enhance the operation frequency. Further, 2D materials are good candidates to replace
traditional semiconductors for resonant tunneling diodes (RTDs) since that realizing the negative differential
resistance (NDR) phenomenon in a resonant tunneling diode (RTD) at room temperature has been challenging
due to carrier scattering related to interfacial imperfections.
10-12
This is unavoidable in the study of conductive
semiconductor heterostructures using advanced epitaxial growth techniques. However, one of 2D material
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Frequently asked questions

Q1. What are the contributions in "Atomic-monolayer two-dimensional lateral quasi-heterojunction bipolar transistors with resonant tunneling phenomenon" ?

In this paper, two types of the lateral quasiheterojunction bipolar transistor, n-p-n and p-n-p, are meticulously fabricated and studied in the same piece of a tabletop, in order to compare the device performance between them. 

Q2. What future works have the authors mentioned in the paper "Atomic-monolayer two-dimensional lateral quasi-heterojunction bipolar transistors with resonant tunneling phenomenon" ?

The results are fascinating and promising for the future development of electronics based on the concept of quasi- heterojunction bipolar transistor using a monolayer 2D lateral heterojunctions.