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Cubic and hexagonal boron nitride (cBN and hBN) heterojunctions to n-type Si are fabricated under low-energy ion bombardment by inductively coupled plasma-enhanced chemical vapor deposition using the chemistry of fluorine. The sp2-bonded BN/Si heterojunction shows no rectification, while the cBN/sp2BN/Si heterojunction has rectification properties analogue to typical p-n junction diodes despite a large thickness (∼130 nm) of the sp2BN interlayer. The current-voltage characteristics at temperatures up to 573 K are governed by thermal excitation of carriers, and mostly described with the ideal diode equation and the Frenkel-Poole emission model at low and high bias voltages, respectively. The rectification in the cBN/sp2BN/Si heterojunction is caused by a bias-dependent change in the barrier height for holes arising from stronger p-type conduction in the cBN layer and enhanced with the thick sp2BN interlayer for impeding the reverse current flow at defect levels mainly associated with grain boundaries.

Heterojunctions of p-type cubic boron nitride (cBN) and n-type silicon with sp2-bonded BN (sp2BN) interlayers are fabricated under low-energy ion impact by plasma-enhanced chemical vapor deposition, and their rectification properties are studied at temperatures up to 573 K. The rectification ratio is increased up to the order of 105 at room temperature by optimizing the thickness of the sp2BN interlayer and the cBN fraction for suppressing the reverse leakage current. A highly rectifying p-type cBN/thick sp2BN/n-type silicon junction diode shows irreversible rectification properties mainly characterized by a marked decrease in reverse current by an order of magnitude in an initial temperature ramp/down cycle. This irreversible behavior is much more reduced by conducting the cycle twice or more. The temperature-dependent properties confirm an overall increase in effective barrier heights for carrier injection and conduction by biasing at high temperatures, which consequently increases the thermal stability of the diode performance.

SummaryThis paper describes a simple method to accurately simulate the flow field around a wing in surface effect ship (Wises) model that involves the use of a contraction and a slot to suck the boundary layer from a flat plate. Theoretical aspects of the design are discussed with relation to the required level of suction and the slot width.The effectiveness is ascertained from measurements of the boundary layer height on the plate through measurement of the mean velocity profile and a reduction in height of 50% was generally observed when suction was used.Comparison of the forces on a low aspect-ratio wing, obtained from the proposed and the image method, verified the proposed method for wing heights above 2·5% of the mean chord. At lower heights, separation of the boundary layer on the ground plate is thought to have altered the pressure distribution on the wing.

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