High-Performance Germanium Thin-Film Transistors With Single-Crystal-Like Channel via Continuous-Wave Laser Crystallization

Li, Yi-Shao; Wu, Chun-Yi; Liao, Chan; Huang, Wen Chang; Shieh, Jia‐Min; Chou, Chang‐Pin; Chuang, Kai-Chi; Luo, Jun-Dao; Cheng, Huang–Chung

doi:10.1109/led.2018.2873945

Cited by 11 publications

(13 citation statements)

References 18 publications

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“…Then, the pre-melted Ge (i.e., past scanning region) which has been solidified acted as the seeds and started to crystallize the as-deposited Ge from the solidified seeds to the current melting Ge. The crystallization direction was consistent with the laser-scanning direction due to the strong thermal gradient from current melting region to the solidified region [26]. Thus, the longitudinal grains along laser-scanning direction with grain width of 2 µm can be obtained in the central region.…”

Section: Resultssupporting

confidence: 65%

“…Thus, many technologies have been proposed to produce high-quality poly-Ge films on insulators in order to improve the performance of poly-Ge TFTs. These technologies include solid phase crystallization (SPC) [15], [16], metalinduced crystallization (MIC) [17], [18], metal-induced lateral crystallization (MILC) [10], [19], lateral liquid-phase epitaxy (LLPE) [20], [21], epitaxial growth with seed layer [22], excimer laser crystallization (ELC) [23], [24], and continuous-wave laser crystallization (CLC) [25], [26]. Unfortunately, SPC requires a long process time for sufficient annealing while the resultant film quality is poor.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization

Liao

et al. 2019

IEEE J. Electron Devices Soc.

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The crystallinity of polycrystalline germanium (poly-Ge) films were demonstrated through continuous-wave laser crystallization (CLC) with Gaussian-distribution beam profile. The different grain sizes of CLC poly-Ge were observed in their three crystallization regions, which were 2 μm, 680 nm, and 90 nm for the central, transition, and edge regions, respectively. Furthermore, the relation between crystallinity and carrier types in these three regions of counter-doped CLC poly-Ge films were investigated. In the central and transition regions, the CLC poly-Ge films with relatively low hole concentration were easily converted to n-type poly-Ge films through a counter-doping process. In contrast, the edge region with poor crystallinity exhibited p-type behavior due to high defect-generated hole concentration. According to these material properties of counter-doped CLC poly-Ge films, the corresponding transfer characteristics of p-channel poly-Ge thin-film transistor for three crystallization regions were further investigated. Subsequently, high-performance p-channel poly-Ge thin-film transistors in the central region exhibited a superior field-effect mobility of 792.2 cm 2 /V-s.INDEX TERMS Polycrystalline germanium (poly-Ge), continuous-wave laser crystallization (CLC), counter-doping (CD), thin-film transistor (TFT).

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization

Liao

et al. 2019

IEEE J. Electron Devices Soc.

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“…Published studies have purposed the fabrication of highquality Ge as the GeOI devices for future ICs, such as solidphase crystallization (SPC) [8], metal-induced crystallization (MIC) [9], lateral liquid-phase crystallization (LLPE) [10], [11], layer transfer technique [12], and laser crystallization (LC) [13]- [15]. Unfortunately, both SPC and MIC required long-time annealing, and the quality of crystallized Ge films was thought to be relatively poor; LLPE could attain highquality Ge films, whereas its process temperature of nearly 1000 ℃ to melt the Ge was unfavorable for the monolithic 3D integration; the layer transfer technique suffered complicated fabrication process.…”

Section: Introductionmentioning

confidence: 99%

High-Performance P-Type Germanium Tri-Gate FETs via Green Nanosecond Laser Crystallization and Counter Doping for Monolithic 3-D ICs

Chung

Pan

Lin

et al. 2023

IEEE J. Electron Devices Soc.

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This paper proposed a fabrication of p-type Germanium (Ge) tri-gate field-effect transistors (Tri-gate FETs) via green nanosecond laser crystallization (GNSLC) and counter doping (CD). By using the GNSLC, the nano-crystalline-Ge (nc-Ge) with a grain size of 80 nm could be turned into polycrystalline Ge (poly-Ge) with that of above 1 μm. With the increase of laser power, the improved crystallinity and lower hole concentration of poly-Ge were also verified by Raman spectra and Hall measurement. To fabricate the high-performance Ge Tri-gate FETs, the chemical-mechanical planarization (CMP) and counter doping (CD) process would further be utilized. The CMP process eliminated the surface roughness of poly-Ge while the CD process decreased the hole concentration of poly-Ge or even converted that into an N-type one. The effect of the CD on the performance of ptype Ge Tri-gate FETs was further investigated. Consequently, the GNSLC Ge Tri-gate FETs showed threshold voltage (Vth) of -0.41 V, ION of 7.10×10 -6 , and IOFF of 1.28×10 -9 respectively, indicating better crystallinity of the Ge channel.

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“…GERMANIUM (Ge) has exhibited advantages of higher carrier mobility and lower processing temperature compared with Si devices. These make Ge to be an alternative for applications of ultrascaled CMOS logic devices and thin-film transistors (TFTs) as top layer in threedimensional integrated circuits [1][2][3]. In the past few years, great efforts have been focused on surface passivation, gate dielectric, and channel engineering for Ge p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs), which have contributed to significant improvement in electrical performance for the p-channel devices.…”

Section: Introductionmentioning

confidence: 99%

Ge N-Channel MOSFETs with ZrO2 Dielectric Achieving Improved Mobility

Chou

Liu

et al. 2021

Nanoscale Res Lett

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High-mobility Ge nMOSFETs with ZrO2 gate dielectric are demonstrated and compared against transistors with different interfacial properties of ozone (O3) treatment, O3 post-treatment and without O3 treatment. It is found that with O3 treatment, the Ge nMOSFETs with ZrO2 dielectric having a EOT of 0.83 nm obtain a peak effective electron mobility (μeff) of 682 cm2/Vs, which is higher than that of the Si universal mobility at the medium inversion charge density (Qinv). On the other hand, the O3 post-treatment with Al2O3 interfacial layer can provide dramatically enhanced-μeff, achieving about 50% μeff improvement as compared to the Si universal mobility at medium Qinv of 5 × 1012 cm−2. These results indicate the potential utilization of ZrO2 dielectric in high-performance Ge nMOSFETs.

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High-Performance Germanium Thin-Film Transistors With Single-Crystal-Like Channel via Continuous-Wave Laser Crystallization

Cited by 11 publications

References 18 publications

Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization

Effects of Crystallinity on the Electrical Characteristics of Counter-Doped Polycrystalline Germanium Thin-Film Transistor via Continuous-Wave Laser Crystallization

High-Performance P-Type Germanium Tri-Gate FETs via Green Nanosecond Laser Crystallization and Counter Doping for Monolithic 3-D ICs

Ge N-Channel MOSFETs with ZrO2 Dielectric Achieving Improved Mobility

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