Optical property of hexagonal (2H) silicon crystal

Abstract

Hexagonal (2H) silicon (Si) semiconductors have excellent mechanical properties and optically diverse applications due to their structure and quasi-direct bandgap. The 2H-Si has a relatively lower direct band gap of approximately 1.69 eV at the Γ-point in comparison with that of diamond-silicon (i.e. 3.4 eV), but it is not actually a direct bandgap semiconductor. Herein, we report an optical property of wide spectrum light emission in visible and infrared ranges from grown Si crystals with a 2H structure of a 0 = 0.3824 nm, c 0 = 0.6257 nm, and c 0/a 0 = 1.6362 corresponding to theoretical predictions and experimental results. Obtained via high-resolution transmission electron microscopy measurements, the crystal structure of the grown 2H Si possesses the only stable form of the 2H structure with the characteristic quasi-direct bandgap, achieved using mixed-source hydride vapor phase epitaxy at about 1200 °C. Raman, photoluminescence, and electroluminescence spectra, Commission International de l’ Eclairage chromaticity coordinates of light emission, lattice parameters, and the quality of the crystals were evaluated and found to correspond with the predicted results. The reported material has potential applications in optoelectronics.