Formation of a resonant microcavity in hydrogen ion-implanted silicon-on-insulator structures

Studies have been carried out on silicon-on-insulator (SOI) structures after the implantation of 24 keV, 3×10^17 cm−2 hydrogen ions, and annealing at temperatures of 200−1000 °C in an argon ambient at either atmospheric pressure or under conditions of hydrostatic compression at 6 and 12 kbar. Photoluminescence (PL), Raman spectroscopy, secondary ion mass spectrometry, and high-resolution electron microscopy have been used to characterize the optical and structural properties of the resulting SOI structures. It has been found that annealing at a pressure above 6 kbar leads to a wavelength-selective increase (up to 37×) in the intensity of the PL from hydrogen implanted SOI samples. The appearance of fine structure in the PL spectrum correlates with the impeded outdiffusion of hydrogen from the implanted top Si layer as well as with the suppressed process of hydrogen microbubble formation in the near-surface region as a result of the annealing at a pressure P>6 kbar. These processes enable one to fabricate an optical resonant microcavity with mirrors formed by the air/silicon and the top Si layer/SiO2 interfaces, and the optically active layer resulting from the implantation of hydrogen and the subsequent annealing. Theoretical calculations of the PL spectra in the resonator help explain some of the specific spectral features. The mechanism of the observed photoluminescence has been discussed in terms of recombination processes occurring in nanometer-sized amorphous silicon regions saturated with hydrogen.