Electrical and Structural Characteristics of Excimer Laser-Crystallized Polycrystalline Si1−xGex Thin-Film Transistors

Abstract

We investigated the characteristics of excimer laser-annealed polycrystalline silicon–germanium (poly-Si1−xGex) thin film and thin-film transistor (TFT). The Ge concentration was increased from 0% to 12.3% using a SiH4 and GeH4 gas mixture, and a Si1−xGex thin film was crystallized using different excimer laser densities. We found that the optimum energy density to obtain maximum grain size depends on the Ge content in the poly-Si1−xGex thin film; we also confirmed that the grain size of the poly-Si1−xGex thin film is more sensitive to energy density than the poly-Si thin film. The maximum grain size of the poly-Si1−xGex film was 387.3 nm for a Ge content of 5.1% at the energy density of 420 mJ/cm2. Poly-Si1−xGex TFT with different Ge concentrations was fabricated, and their structural characteristics were analyzed using Raman spectroscopy and atomic force microscopy. The results showed that, as the Ge concentration increased, the electrical characteristics, such as on current and sub-threshold swing, were deteriorated. The electrical characteristics were simulated by varying the density of states in the poly-Si1−xGex. From this density of states (DOS), the defect state distribution connected with Ge concentration could be identified and used as the basic starting point for further analyses of the poly-Si1−xGex TFTs.

On the thermoelectric alloy SixGe1-x

“…SixGe1-x composites are wiedly used in thermogenerators, coolers, sensors, 1,2 thin-film transistors, 3 batteries, 4 solar cells, 5,6 photodetectors 7,8 and others. These alloys are good high-temperature materials for the temperature range up to 1200℃.…”

The Electronic Properties of Boron-Doped Germanium Nanocrystals Films

“…In the past ten years, more and more attention has been focused on the Silicon-based and Germanium-based semiconductor nanocrystals since they can be used in many kinds of devices such as light emitters, thin-film solar cells, photoelectric sensors, as well as nonvolatile memories [1][2][3][4][5][6][7]. Compared with Si, Ge has larger electron and hole mobility, a narrower band-gap (0.67 eV) as well as high phonon responsivity in the near-infrared region [8][9][10], which is beneficial to fabricate Ge-based photodetectors and Ge-based thin film transistor (TFT) with good device performance [11][12][13][14]. In order to further enhance the performance of devices based on Si and Ge NCs, active doping is usually required to obtain all kinds of desired properties of the Si and Ge NC materials [15][16][17][18].…”

(Invited, Digital Presentation) Evaluation of Polycrystalline-Si1-XGex Thin-Film Transistors Grown Laterally on a Glass Substrate Using a Continuous-Wave Laser

“…Moreover, the fabrication of a stable gate dielectric GeO2 is highly challenging. Therefore, the addition of Ge to Si is expected to be a promising approach for the performance enhancement of Si-based TFTs, and several studies have been reported on the performance of poly-Si1-xGex TFTs (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). This study aims to understand the performance of CLC poly-Si1-xGex TFTs and highlight the issues pertaining to CLC poly-Si1-xGex thin films by comparing the performance of CLC poly-Si1-xGex TFTs with that of CLC poly-Si TFTs.…”