Electronic properties of metal/sol‐gel SiO2/indium‐phosphode capacitor

This work reports on the electrical properties of metal-oxide-semiconductor (MGS) capacitors made with a spin-on-glass (SGG) SiO, layer, doped with 2% phosphorus, deposited on InP substrate by spin casting followed by a low-temperature ( < 260 “C) anneal. The capacitance versus voltage behavior as well as the dielectric constant of the SOG layer was analyzed as a function of the frequency. The stability of the relevant parameters was checked after a long period of time (four weeks), compared with fresh devices, and revealed a significant increase in the dielectric constant and a slight increase in the leakage current. It is shown that the use of SOG as the dielectric material in the MOS structure leads to a relatively low fixed charge (less than 2x 10” cm - 2 1 and low fast state concentration. Indium-phosphide (InP) metal-insulator-semiconductor field-effect transistor (MISFETs) have important potential applications in high-frequency digital circuits, microwave power amplifiers, and monolithic optoelectronics circuits. High electron mobility (5200 cm/V s) and high saturation velocity (2.5 X 10’ cm/s) are the two key properties which make InP attractive for this application. The InP MISFETs can be readily configured for enhancement-mode operation, thus allowing low-power dissipation to be achieved in digital circuits. As a result of the insulated gate, a large dynamic range for the circuit can be achieved leading to a larger logic swing and consequently better noise margins. The larger breakdown voltage, higher thermal conductivity, and lower ionization coefficient compared to GaAs make InP a better choice for microwave power generation. The semi-insulating nature of InP makes circuit isolation easy and minimizes cross talk. InP is expected to play an important role in optical fiber telecommunications since the long-wavelength optical devices use InP as the substrate. The band-gap energy of InP-based alloys is near the wavelength of minimum loss in optical fibers. For example, monolithic integration of an InGaAs