Reactively sputtered AlN is shown by electrical characterization of Pt/Au Schottky diodes to be an effect encapsulant for GaN annealed at 1100 °C. Schottky diodes formed on GaN encapsulated with AlN during the anneal had low reverse leakage currents with breakdown voltages in excess of 40 V. In contrast, samples annealed without the AlN layer had 3–4 orders-of-magnitude higher reverse leakage currents. Atomic force microscopy images of as-grown and annealed samples also demonstrate an increase in surface roughness and a change in morphology of the uncapped samples following annealing. Auger electron spectroscopy supports the hypothesis that the AlN encapsulant is reducing N loss from the GaN substrate. N loss in the uncapped samples is expected to create an n+-region at the surface that accounts for the high reverse leakage current and improved Ohmic behavior for the uncapped samples. The use of AlN encapsulation will enable the realization of all ion implanted GaN metal semiconductor field effect transistors.

Specular, crack-free thin films of the refractory conductor zirconium boride have been deposited for possible applications in combined contact/diffusion barrier metallization schemes. Films were deposited by dc triode sputtering, which allowed the independent study of the effects of sputtering pressure, target voltage, and current on the film properties. The mole ratio of boron in the films increased (composition tending to ZrB2) and the resistivity decreased with increasing deposition rates which at a fixed target voltage and sputtering pressure increased almost linearly with target current. Decrease in sputtering pressure, with only a minor change in deposition rate, dramatically decreased resistivity and caused stress in the films to change from tensile to compressive. X-ray photoelectron spectroscopy correlated reduced oxygen content to reduced resistivity. Triode sputtering permitted deposition of films at 2 mTorr with a resistivity of 162 μΩ cm which is the lowest reported value for as-deposited films.

Articles you may be interested inDependence of selectivity on plasma conditions in selective etching in submicrometer pitch grating on InP surface by CH4/H2 reactive ion etching J. Appl. Phys. 109, 073516 (2011); 10.1063/1.3573536 X-ray photoelectron spectroscopy damage characterization of reactively ion etched InP in CH 4 -H 2 plasmas

Exposure to a hydrogen plasma at 250 °C of p-type GaN (Ca) prepared by either Ca+ or Ca+ plus P+ co-implantation leads to a reduction in sheet carrier density of approximately an order of magnitude (1.6×1012 cm−2 to 1.8×1011 cm−2), and an accompanying increase in hole mobility (6 cm2/V s to 18 cm2/V s). The passivation process can be reversed by posthydrogenation annealing at 400–500 °C under a N2 ambient. This reactivation of the acceptors is characteristic of the formation of neutral (Ca–H) complexes in the GaN. The thermal stability of the passivation is similar to that of Mg–H complexes in material prepared in the same manner (implantation) with similar initial doping levels. Hydrogen passivation of acceptor dopants in GaN appears to be a ubiquitous phenomenon, as it is in other p-type semiconductors.

A number of new selective wet etching solutions for AIInP over GaAs and InGaP have been investigated. We find that in addition to HCI and Br2-MeOH, the following room temperature acids also etch AIInP lattice matched to GaAs : HF, HI, H2SO4, HsPO4 and C6H807 (citric acid). Selective etching over GaAs can be obtained with HF, HI, HsPO4 and C6H807, while use of HF, HI, H2SO4, H3PO4, and CeHeO7 provides selectivity over InGaP. The etching of AIInP in HsPO4 is thermally activated, and has the form R o~ exp (-Ea/kT), where Ea = 12.03 kcal 9 moF 1, consistent with the rate-limiting step being chemical reaction at the AIInP surface.