Photon energy dependence of crystallization of Si_1−xGe_xfilms by soft X-ray irradiation

Abstract

Amorphous silicon germanium (a-Si1−xGex) films were crystallized by irradiation with soft X-rays of various photon energies. The crystallization upon soft X-ray irradiation is related to Ge concentration, photon energy, and photon flux density. The Ge atom was the trigger for the crystallization of the SiGe film because the atomic migration of Ge atoms was enhanced by electron excitation during soft X-ray irradiation, compared with Si atoms. As the photon energy decreased from 130 to 50 eV, the crystalline fraction increased. In the Si0.5Ge0.5 film, the ratio of peaks attributable to the crystal phases to those attributable to the amorphous phases of Si–Si, Si–Ge, and Ge–Ge bonds changed with irradiated photon energy. This is explained by the relationship between the orbital energies of Si 2p and Ge 3d and the photon energy of irradiated soft X-rays, because the electron excitation probability was determined by this relationship. Therefore, it is considered that soft X-ray irradiation crystallization occurred via the exitation of electrons from the core level.

Review—Technology Trends of Poly-Si TFTs from the Viewpoints of Crystallization and Device Performance

“…We also observed this phenomenon by comparing ELA crystallized films of the a-Si films deposited by PECVD and by LPCVD. 22 Soft X-ray crystallization 20,23,[47][48][49][50][51][52][53][54][55] .-In this section, we discuss why soft X-ray crystallization (SXC) is the optimum low-temperature crystallization method for the era of flexible electronics and how it differs from the conventional thermal crystallization method such as RTA, ELA and SPC.…”

(Invited) Technology Trend of Poly-Si TFT from Viewpoints of Crystallization and Device Performance

“…Low-temperature crystallization -SXC- [24][25][26][27][28][29][30][31][32] Fig. 4 shows the relationship between the crystalline fraction and saturated temperature for the SXC.…”

Low-temperature activation of boron ion in silicon substrate using B10H14 + cluster and by soft X-ray irradiation

“…It was clarified that the threshold temperature for the crystallization of Si, Ge, and Si 1−x Ge x was decreased by approximately 100 °C in comparison with a conventional furnace annealing. [18][19][20][21][22][23][24] The excitation of core electrons by soft X-ray irradiation enhances local atom movement and enables lowtemperature crystallization. In addition, compact soft X-ray sources, called laser plasma X-rays (LPXs), have been developed for next-generation processes such as extreme ultraviolet lithography.…”