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Investigates the higher order bands (HOB) in irradiated Czochralski silicon. Use of Fourier transform infrared absorption spectroscopy and Hall-effect measurements; Factors attributing to the creation of higher order bands; Photoexcitation and decay characteristics of HOB and the thermal donors.

Comments on J.K. Lao and colleagues' article 'Piezoelectric Effect on AlInGaN/GaN Heterostructures.' Effect of a small fraction of In atoms in AlInGaN/GaN on the piezoelectric field at the interface; Schematic illustration of the band structure in the triangular potential quantum well; Origin of the beating oscillations; Zero-magnetic-field spin splitting.

Al and GaN contacts on both Si(111) and sapphire substrates were studied in this letter. After annealing at 450, 520, 600, and 650 °C for 35 min under a N[sub 2] flowing ambient, the current-voltage characteristics of Al/GaN contacts on Si(111) substrates were different from those on sapphire ones. The interfacial properties were discussed using the Schottky emission model in which the current is proportional to the square of the applied voltage. The metallurgical reactions were analyzed using photoluminescence (PL) spectra and x-ray diffraction (XRD). After annealing, blueshifts in the PL spectra and new peaks in the XRD data indicated that the wide-band gap interfacial phase AlGaN was formed at the Al/GaN interface. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A metal-ferroelectric-semiconductor (MFS) structure has been developed by depositing SrBi[sub 2]Ta[sub 2]O[sub 9] (SBT) films directly on n-type (100) Si by pulsed laser deposition. In the MFS structure, evidence for ferroelectric border traps in the SBT film has been obtained by high-frequency capacitance-voltage (C-V) measurement. When the ramp rate of voltage is higher than 200 mV/s, typical ferroelectric C-V hysteresis loops with the counterclockwise direction are obtained in C-V plots. When the ramp rate is lower than 80 mV/s, the ferroelectric hysteresis loops are replaced by the trap-induced ones with the clockwise direction. This pronounced change results from the fact that more and more border traps in SBT can communicate with the underlying Si. The border-trap density at the ramp rate of 10 mV/s is as high as 1.8x10[sup 12] cm[sup -2]. Moreover, the width of the hysteresis loops changes linearly with the logarithmic decrease in ramp rate, which is consistent with the ferroelectric border traps communicating with Si by tunneling or a thermally activated process. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

GaN metal-semiconductor-metal photoconductive detectors have been fabricated on Si(111) substrates. The GaN epitaxial layers were grown on Si substrates by means of metalorganic chemical-vapor deposition. These detectors exhibited a sharp cutoff at the wavelength of 363 nm and a high responsivity at a wavelength from 360 to 250 nm. A maximum responsivity of 6.9 A/W was achieved at 357 nm with a 5 V bias. The relationship between the responsivity and the bias voltage was measured. The responsivity saturated when the bias voltage reached 5 V. The response time of 4.8 ms was determined by the measurements of photocurrent versus modulation frequency. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The characteristics of low-frequency noise in n-metal-oxide-semiconductor field-effect transistors with ultranarrow channels have been investigated through random telegraph signals and low-frequency noise spectroscopy. Random telegraph signals with very large amplitude (∼70%) are observed in weak inversion at room temperature. Low-frequency noise spectra having both 1/f[sup n] and Lorentzian type are found separately in the same channel at various gate bias voltages. The observations strongly suggest that the low-frequency noise is dominated by carrier mobility fluctuation in weak inversion and by carrier number fluctuation under high-field conditions in an ultranarrow channel. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]