Browsing by Author "Tang, Hao-Ling"

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Analysis of Relative Intensity Noise Spectra for Uniformly and Chirpily Stacked InAs-InGaAs-GaAs Quantum Dot Lasers
(2012-02-01)
Lin, Gray
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Tang, Hao-Ling
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Cheng, Hsu-Chieh
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Chen, Hung-Lin
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電子工程學系及電子研究所
The dynamic properties of uniformly and chirpily stacked InAs-InGaAs-GaAs quantum dot lasers are analyzed in terms of relative intensity noise spectra. For uniformly stacked quantum dot laser with ground-state lasing emissions of 1.3 mu m, the K-factor limited bandwidth is 13 GHz. The extracted differential gain and gain compression factor are 1.7 x 10(-15) cm(2) and 2 x 10(-16) cm(3), respectively. For chirpily stacked quantum dot laser with excited-state lasing emissions of 1.2 mu m, the K-factor limited bandwidth is 14 GHz. Yet the nonproportional dependence between resonance frequency and square root of incremental current yields differential gain of 4.3 x 10(-15) cm(2) and huge gain compression factor of 1.4 x 10(-14) cm(3).
Band Alignment of 2D Transition Metal Dichalcogenide Heterojunctions
(2017-05-18)
Chiu, Ming-Hui
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Tseng, Wei-Hsuan
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Tang, Hao-Ling
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Chang, Yung-Huang
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Chen, Chang-Hsiao
It is critically important to characterize the band alignment in semiconductor heterojunctions (HJs) because it controls the electronic and optical properties. However, the well-known Anderson's model usually fails to predict the band alignment in bulk HJ systems due to the presence of charge transfer at the interfacial bonding. Atomically thin 2D transition metal dichalcogenide materials have attracted much attention recently since the ultrathin HJs and devices can be easily built and they are promising for future electronics. The vertical HJs based on 2D materials can be constructed via van der Waals stacking regardless of the lattice mismatch between two materials. Despite the defect-free characteristics of the junction interface, experimental evidence is still lacking on whether the simple Anderson rule can predict the band alignment of HJs. Here, the validity of Anderson's model is verified for the 2D heterojunction systems and the success of Anderson's model is attributed to the absence of dangling bonds (i.e., interface dipoles) at the van der Waal interface. The results from the work set a foundation allowing the use of powerful Anderson's rule to determine the band alignments of 2D HJs, which is beneficial to future electronic, photonic, and optoelectronic devices.
Metal-Guided Selective Growth of 2D Materials: Demonstration of a Bottom-Up CMOS Inverter
(2019-05-03)
Chiu, Ming-Hui
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Tang, Hao-Ling
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Tseng, Chien-Chih
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Han, Yimo
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Aljarb, Areej
2D transition metal dichalcogenide (TMD) layered materials are promising for future electronic and optoelectronic applications. The realization of large-area electronics and circuits strongly relies on wafer-scale, selective growth of quality 2D TMDs. Here, a scalable method, namely, metal-guided selective growth (MGSG), is reported. The success of control over the transition-metal-precursor vapor pressure, the first concurrent growth of two dissimilar monolayer TMDs, is demonstrated in conjunction with lateral or vertical TMD heterojunctions at precisely desired locations over the entire wafer in a single chemical vapor deposition (VCD) process. Owing to the location selectivity, MGSG allows the growth of p- and n-type TMDs with spatial homogeneity and uniform electrical performance for circuit applications. As a demonstration, the first bottom-up complementary metaloxide-semiconductor inverter based on p-type WSe2 and n-type MoSe2 is achieved, which exhibits a high and reproducible voltage gain of 23 with little dependence on position.
Room-Temperature Ferroelectricity in Hexagonally Layered alpha-In2Se3 Nanoflakes down to the Monolayer Limit
(2018-12-12)
Xue, Fei
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Hu, Weijin
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Lee, Ko-Chun
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Lu, Li-Syuan
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Zhang, Junwei
2D ferroelectric material has emerged as an attractive building block for high density data storage nanodevices. Although monolayer van der Waals ferroelectrics have been theoretically predicted, a key experimental breakthrough for such calculations is still not realized. Here, hexagonally stacking alpha-In2Se3 nanoflake, a rarely studied van der Waals polymorph, is reported to exhibit out-of-plane (OOP) and in-plane (IP) ferroelectricity at room temperature. Ferroelectric multidomain states in a hexagonal alpha-In2Se3 nanoflake with uniform thickness can survive to 6 nm. Most strikingly, the electric-field-induced polarization switching and hysteresis loop are, respectively, observed down to the bilayer and monolayer (approximate to 1.2 nm) thicknesses, which designates it as the thinnest layered ferroelectric and verifies the corresponding theoretical calculation. In addition, two types of ferroelectric nanodevices employing the OOP and IP polarizations in 2H alpha-In2Se3 are developed, which are applicable for nonvolatile memories and heterostructure-based nanoelectronics/optoelectronics.