Silicon Rich Oxide (SRO) has luminescent properties that can be used in silicon optoelectronics devices. Nowadays the emission mechanisms are not completely understood, leading to a high potential field of research. The study of the SRO characteristics and its relation with the emission would provide information on the mechanism of radiation.
In this work the optical properties of SRO are studied. Photoluminescence (PL), transmittance and refractive index of silicon rich oxide films annealed at high temperature during different times have been obtained. PL spectra show a considerable emission of visible light with different thermal treatment times and have a wide wavelength spectrum from 400 to 600 nm (3.1-2 eV ) and 650 to 850 nm (1.9-1.45 eV). Absorption spectra were studied and the optical band gap was determined. It can be seen that the optical band gap determined from these spectra changes as the silicon excess varies. The refractive index of SRO films also augments with the excess of silicon, and with the thermal treatments time.
New silicon based optical sensors with a metal - insulator - semiconductor structure (MIS) are developed and investigated both theoretically and experimentally. The physical properties of these sensors are described with a model of MIS capacitor where a presence of depletion layer of electrons and an inversion layer of holes of a finite depth is taken into account. Two-level voltage bias provides a transient between two quasi-equilibrium inversion modes. This transient is applied both for storage and for readout of the input optical signal for quantitative measurements of a weak infra red radiation. Proposed simple readout procedure provides reading the integrated information with a significant amplification. The amplification (or the current transformation coefficient) is determined by the ratio of integration and readout times and it may exceed 104. A theoretical model is given to explain a behavior of the sensor under storage by thermo generated carries and by photo generated ones jointly. Numerical simulations are of an agreement with experimental investigations of proposed sensors.
Theoretical model of a new high-speed metal - insulator - semiconductor (MIS) radiation sensor possessing giant internal signal amplification is proposed to describe the experimentally obtained results. The sensor is fabricated on an Ultra-High Resistivity (UHR) Epi Layer (>10 kΩ cm) on a heavily doped wafer. Theoretical modeling explains the giant value of the internal amplification of the signal that is determined as the ratio of peak values of readout currents and instantaneous photo current. At the integration time about 1 sec the amplification coefficient is of the order of 104 in the case of the external load 10 - 50 kΩ, and it is of the order of 106 when the external load is smaller than 1 kΩ. The sensors operate under non-modulated radiation as well as under an optical signal modulation till 1 GHz.
We present a new near-infrared photodetectors fabricated based on Hg3In2Te6 semiconductor compound. This ternary compound is a direct-gap n-type semiconductor with the band gap of 0.74 eV and carrier concentration about 1013 cm-3 at room temperature. Surface-barrier structures a transparent conducting metal oxide electrode-interfacial chemical grown oxide-semiconductor substrate with an active area from 3 to 50 mm2 have been fabricated by chemical oxidation of Hg3In2Te6 surface for the potential barrier's formation. The composition of oxide layer (40% In2O3, 50% TeO2, and 10% HgO) was determined using XPS analysis. Tin-doped indium oxide (ITO) film (as transparent conducting electrode) was deposited over this layer by magnetron RF sputtering technique. The devices are very sensitive to light with the wavelength from 0.4 to 1.7 micrometer. A self-calibrated photodetectors, which permit 100% external quantum efficiency (within error not exceeding 2%) at wavelengths of 1.3 and 1.5 micrometer, have been developed. The photodetectors fabricated on thin Hg3In2Te6 substrates have a low producing price and can be fabricated with a large photosensitive area. Photodetectors with an active area of 3 mm2 exhibit the rise and fall times from 2 to 4 ns under 1.3 micrometer pulse irradiation. Both basic material aspects and devices fabrication technique is detailed discussed.