Chien-Te Ku

Luminescence mechanisms of silicon-rich nitride films fabricated by atmospheric pressure chemical vapor deposition in N2 and H2 atmospheres

This work examines possible luminescence mechanisms of silicon-rich nitride (SRN) films that were fabricated by atmospheric pressure chemical vapor deposition (APCVD). Under an ambient gas of either H2 or N2, two SRN films were deposited using the same precursors of Si and N. While photoluminescence (PL) measurements of both as-deposited specimens revealed an intense luminescence band (1.8–3.8 eV), which was observable by the naked eye, a detailed examination of the high energy band of the PL spectra over 2.8 eV yielded different results for those samples that were fabricated in different ambiences. To determine the reason for these differences, Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy were conducted, suggesting unique chemical bonds and elemental ratio of nitrogen to silicon in SRN films. Further analysis involving plan-view high-resolution transmission electron microscopic observations of SRN films demonstrated the embedding of Si quantum dots (Si QDs), but with some ...

Growth of InN on Si (111) by atmospheric-pressure metal-organic chemical vapor deposition using InN/AlN double-buffer layers

Indium nitride (InN) epilayers have been successfully grown on Si (111) substrates with low-temperature (450°C) grown InN and high-temperature (1050°C) grown AlN (InN∕AlN) double-buffer layers by atmospheric-pressure metal-organic chemical vapor deposition (AP-MOCVD). X-ray diffraction characterizations indicated that highly (0001)-oriented hexagonal InN was grown on Si (111) substrate. Photoluminescence (PL) analyses performed at room temperature showed a strong emission at 0.72eV with a full width at half maximum of 121meV. Excitation intensity dependent measurements demonstrated the PL mechanism to be the band-to-band transition. Time-resolved PL could be fitted by a single exponential exhibiting an ordered film and a recombination lifetime of around 0.85ns. In particular, transmission electron microscopy characterizations indicated that the use of AlN first buffer is very important to achieve a structurally uniform (0001)-oriented InN epilayer on Si (111) by AP-MOCVD.

Luminescence Mechanism of SiOx Films Grown by Atmospheric-Pressure Halide Chemical Vapor Deposition

Strong red-light luminescence was exhibited by nonstoichiometric silicon oxide (SiOx) films grown by atmospheric-pressure halide chemical vapor deposition. The temperature-dependent photoluminescence (PL) measurements and theoretical calculation of emission energy demonstrated that the PL of our samples originated from the energy level of the interface between Si quantum dots (Si-QDs) and a SiO2 matrix. Moreover, the continuous-wave PL spectra showed that the PL intensity can be enhanced by thermal annealing in CO2 environment. The radiative lifetime determined from the time-resolved PL measurement was increased by increasing CO2 thermal annealing temperature. The high-resolution transmission electron microscopy showed single-crystalline Si-QDs embedded in the SiOx films. According to the results obtained, the emission peak of the PL spectra of the SiOx films was probably due to the energy level of the interface region transition, and the nonradiative centers (or dangling bond, defect center) can be passivated using CO2 thermal annealing.