This work characterizes a GaN:Mg on silicon ultraviolet photodetector with a cutoff at 3.3 eV and a responsivity of 12 A/W at 4 V bias for optical intensities on the order of 1 W/m2 and below. A weak photovoltaic response is also reported. The photocurrent is nearly linear versus optical intensity for up to 10 W/m2. The responsivity increases nearly linearly with applied voltage up to 8 V, then the increase slows toward saturation. To explain this high responsivity in a direct gap semiconductor, it is hypothesized that holes are captured at either compensated Mg deep acceptor sites or Mg-related trap/recombination centers, resulting in a greatly prolonged electron free-carrier lifetime.

Wurtzite GaN films on AlN buffer layers were grown on Si(111) by plasma-assisted molecular beam epitaxy. High resolution x-ray diffraction and scanning electron microscope studies indicate that the mosaic disorder decreases with increasing film thickness and increasing growth temperature. The grain size increases with the growth temperature. The best (0002) diffraction peak full width at half-maximum is 22 arcmin for a film 1.7 μm thick. Prominent low-temperature exciton luminescence is observed at 3.46 eV. The plasma I-V characteristics are measured with a Langmuir probe near the growth position and analyzed to extract the nitrogen ion density and energy for the growth conditions used.

We have grown monocrystalline AlN on Si (111) substrates over the temperature range 550–900 °C using electron cyclotron resonance plasma assisted molecular beam epitaxy. The best (0002) peak omega rocking curve full width at half-maximum value obtained was 26 min for a film deposited at 900 °C. All films nominally displayed the AlN[0001]∥Si[111] orientation. The exact angle between AlN[0001] and Si[111] decreased from 2.1° to 1.1° and the (0002) peak widths improved with increasing substrate temperature. Mosaic-type disorder was shown by high resolution x-ray diffraction to be the dominant cause of the ω rocking curve peak full widths.

Articles you may be interested inThe influence of the AlN barrier thickness on the polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors Performance of AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistors with AlN gate insulator prepared by reactive magnetron sputtering J. Vac. Sci. Technol. B 29, 01A809 (2011); 10.1116/1.3523362 Metal-organic chemical vapor deposition of quasi-normally-off AlGaN/GaN field-effect transistors on silicon substrates using low-temperature grown AlN cap layers Appl. Phys. Lett. 97, 053502 (2010); 10.1063/1.3475394 AlGaN/GaN heterostructure field-effect transistors on single-crystal bulk AlN

It is demonstrated that the stability of hydrogenated amorphous silicon (a-Si:H) is improved by deposition under the combined conditions of high substrate temperature (e.g., TD=400 °C) and high hydrogen dilution, as are readily achieved in a remote hydrogen plasma reactor. In comparison with optimized films from conventional rf glow discharge deposition (e.g., silane, 230 °C, 2 W), undoped high TD films possess a lower midgap defect density, the dark dc conductivity in n-type (phosphorus-doped) films displays higher equilibration temperatures and longer relaxation times at a given temperature with an activation energy of 1.0 eV, and undoped high TD films have a lower saturated density of light-induced defects. It is proposed that the ability to achieve the improved stability is a consequence of two effects: (1) the use of hydrogen dilution during deposition to maintain the hydrogen concentration in the film near 10 at. % even at 400 °C and (2) the possibility that at high TD’s the hydrogen is more stably incorporated in the random network and/or that the density of weak Si—Si bonds is smaller.

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy -The influence of Si-and Mg-doping J. Appl. Phys. 104, 034309 (2008); 10.1063/1.2953087 III-nitride growth and characteristics on ferroelectric materials using plasma-assisted molecular beam epitaxy

Gas phase chemical reactions, of importance in the deposition of amorphous semiconductors, were studied in a remote hydrogen plasma reactor with electron spin resonance (ESR). The following reactant pairs (and their observed room-temperature rate coefficients) were characterized: (1) H+SiH4(2.4×1011 cm3 mole−1s−1), (2) D+SiH4 (2.1×1011 cm3 mole−1 s−1), and (3) H+C2H2 (1.2×1010 cm3 mole−1 s−1). The interpretation of these coefficients in terms of primary and secondary gas phase reactions is discussed, and the values are compared where possible with previously published data. In addition, the paramagnetic centers of the silicon-based film that is deposited in situ during the ESR measurement can now be microscopically identified in light of recent studies.

The performance of InGaP-based pHEMT's as a function of gate metallization is examined for Mo/Au, Ti/Au, and Pt/Au gates. DC and microwave performance of pHEMT's with 0.7-m gate lengths is evaluated. Transconductance, threshold voltage, f t f t f t , and f max f max f max are found to depend strongly on gate metallization. High-speed performance is achieved, with f t f t f t of 41.3 GHz and f max f max f max of 101 GHz using Mo/Au gates. The difference in performance between devices with different gate metallizations is postulated to be due to a combination of the difference in Schottky barrier heights and different gate-to-channel spacings due to penetration of the gate metal into the InGaP barrier layer.