Piezoelectric surface barrier lowering applied to InGaN/GaN field emitter arrays

Abstract

A method of lowering the surface barrier for field emission by using the piezoelectric effect is presented. The piezoelectric effect produces a surface dipole that decreases the surface barrier, which in turn decreases the turn-on voltage of the field emitter. Calculations show that significant reduction of the tunneling barrier can be effected with relatively thin layers of strained InGaN on GaN field emitter arrays. Dramatic reduction of the turn-on voltage from 450 V (GaN field emitter array) to 70 V (InGaN/GaN field emitter array) was observed and can be attributed partly to surface barrier lowering.

Very high efficiency solar cell modules

“…These features include: an existing industry centered around the nitrides; high radiative efficiency even with high dislocation densities; 11 high mobilities, allowing good collection; a large piezoelectric constant, allowing control of surface recombination; 12,13 and the availability of direct high-band gap materials, with band gaps above 2Á4 eV. Such highband gaps are not available in other established material systems, but are necessary for multiple junction solar cells with a large number of cells.…”

Narrow‐band 400 nm MSM photodetectors using a thin InGaN layer on a GaN/sapphire structure

“…Namely, it is speculated that a coherent interface was formed in the case of a 20-nm-thick InGaN layer, whereas in a 50-nm-thick layer, the coherent interface had collapsed and misfit dislocations were introduced because of an accumulated strain energy. Calculations and experimental data suggest that the critical thickness lies in the lower range of 10 nm [5,6].…”

Field emission properties of self-assembled InN nano-structures: Effect of Ga incorporation

“…The growth conditions involved a high V/III ratio of 16,000-18,000, a moderate growth temperature of 550 1C, and a pressure of 200 mbar to yield the desired pyramid geometry of InN. The thickness of InN film was fixed at around 200 nm to eliminate the effect of the piezoelectric field caused by the strain [12], enabling the intrinsic field emission properties of InN to be elucidated directly. In x Ga 1Àx N samples with a Ga content from 2 to 30% were prepared under the same conditions.…”

“…AlN nanotubes and GaN nano-structures were recently proposed to be good vacuum emitters [10,11]. However, only a few field emission studies of InN or In-rich-InGaN nanostructures have been reported [12].…”