Highly oriented lateral growth of SiGe thin films on glass induced by constitutional undercooling

Abstract

Enhanced lateral growth of semiconductor thin films on glass was investigated. The unidirectional growth of silicon (Si) was achieved by introducing continuous-wave laser lateral crystallization. Alloying germanium (Ge) with Si led to highly oriented lateral growth (HOLG) of SiGe thin films. The HOLG and Ge segregation in these films were explained by the constitutional undercooling model. Quasi-single crystals were grown when the Ge mole fraction was 0.3. Using a single scan of the laser on SiGe causes the amorphous phase to become crystal, which tends to decrease the stability of growth. This growth stability was improved by performing multiple scans, where the growth was dominated by regrowth from crystal to crystal.

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

“…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. Part of this study has been reported previously (14)(15)(16)(17)(18)(19)(20). This study presents new data pertaining to crystalline properties of CLC poly-Si1-xGex thin films and performance of pch CLC poly-Si and poly-Si1-xGex TFTs.…”

“…The variation in the intensity of the Raman peak is caused by the surface roughness (21). The crystalline quality and grain sizes of the CLC poly-Si and poly-Si1-xGex films with x=0.05, 0.1, and 0.3 were intensively examined using FE-SEM, EBSD and Raman scattering (15,(17)(18)(19)(20). The grain length of poly-Si1-xGex increased with increasing Ge concentration.…”

“…The grain length of poly-Si1-xGex increased with increasing Ge concentration. For a Ge composition of 0.3, a quasi-singlecrystalline Si film with (111) surface orientation was obtained (17,19).…”

Laser Thermal Processing of Group IV Semiconductors for Integrated Photonic Systems

“…[99] In particular, excimer laser annealing (ELA) has been used to crystallize large areas of a-Si films deposited on glass substrates, leading to the fabrication of low-cost activematrix-driven flat panel displays. [100] A wide range of laser sources operating at UV, visible, and NIR wavelengths, in pulsed and CW modes, has been exploited to crystallize group IV semiconductors, including Si, [101] Ge, [102] SiGe, [103] and GeSn [104,105] thin films and components. These materials have been deposited on both crystalline (i.e., bulk Si) and insulator substrates, which can be further exploited to alter the crystallization process.…”

“…A wide range of laser sources operating at UV, visible, and NIR wavelengths, in pulsed and CW modes, has been exploited to crystallize group IV semiconductors, including Si, [ 101 ] Ge, [ 102 ] SiGe, [ 103 ] and GeSn [ 104,105 ] thin films and components. These materials have been deposited on both crystalline (i.e., bulk Si) and insulator substrates, which can be further exploited to alter the crystallization process.…”