Epitaxy of Al films on GaN studied by reflection high-energy electron diffraction and atomic force microscopy

Abstract

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First-principles calculations of2×2reconstructions of GaN(0001) surfaces involving N, Al, Ga, In, and As atoms

“…This result may explain the low Al surface mobility with respect to Ga in growth over ͑0001͒ planes 39 and in the difficulty in growing good-quality Al films on GaN. 38 Also, independent of the Al concentration and going from Ga-to N-rich conditions, the phase diagram reproduces the previously predicted surface structures ͑Ga monolayer, Ga adatom, and N adatom͒ for clean GaN surfaces with no impurities on the surface. For In substitutions, Fig.…”

“…37 With the Al, In, and As atoms the energies are independent of Ga chemical potential because the stoichiometry of these surfaces differs from the bare surface by the addition of four atoms of Al, In, or As alone. The Al-adlayer structure is stable by 0.07 eV compared to the clean surface, which is one explanation for the poor quality of growth in the first layer in the epitaxy of Al films over clean GaN ͑0001͒ surfaces reported by Liu et al 38 Due to the surfactant behavior of the In and As ͑Ref. 36͒ atoms these adlayer structures are the most stable of all, which is in accordance with the strong 2 ϫ 2 reflection highenergy electron diffraction ͑RHEED͒ pattern 35 of As on GaN surfaces.…”

Behavior of aluminum adsorption and incorporation at GaN(0001) surface: First-principles study

“…Much attempts have been devoted to grow up ultrathin films on GaN substrates. [1][2][3] AlGaN have been under intense investigation owing to its potential in constructing AlGaN/GaN heterostructure devices, [4][5][6][7] such as ultraviolet (UV) light high-temperature/power electronic devices. 5,6 To study the effect of Al doping concentration, there are many reports that Al x Ga 1Àx N/GaN heterostructure grown on sapphire substrate has exhibited excellent device performances, which greatly decreases with Al incorporation.…”

“…Consequently, it is concluded that the growth of 2D hexagonal geometry Al monolayers on GaN(0001) surface is possible. Experimentally, Liu et al3 found that Al films are poor quality at a few coverage; as Al coverage increased, Al growth surface remains relatively flat without any prominent cluster formation and present a characteristics hexagonal geometry. Our results are in good agreement with the experimental results.…”

The role of the tunneling component in the current–voltage characteristics of metal-GaN Schottky diodes

“…C -V measurements can be used to obtain the donor concentration and the barrier height. 7 We have previously studied a variety of metals contacts to n-GaN, such as Pt, Pd, PtSi, Ni, and NiSi [8][9][10] and have determined that the I -V characteristics were strongly dependent on the GaN material quality. From reported results [1][2][3][4][5][6] and our experimental results, it was noted that there is a large scattering in the measured value of the Richardson constant.…”