Activation studies of low-dose Si implants in gallium nitride

Abstract

The implantation of Si ions into undoped high-resistivity GaN films is of interest for the realization of high-performance digital and monolithic microwave integrated circuits. We report the effect of postimplant annealing conditions on the electrical, optical, and surface morphology of Si ion-implanted GaN films. We demonstrate high activation efficiencies for low-dose Si implants into unintentionally doped GaN/sapphire heteroepitaxial films. The Si ions were implanted through an epitaxial AlN cap layer at 100 keV and a dose ∼5×1014 cm−2. Samples were subsequently annealed in an open-tube furnace for various times and temperatures. The postanneal electrical activation is correlated with the surface morphology of the film after annealing. The samples annealed at 1150 °C in N2 for 5 min. exhibited a smooth surface morphology and a sheet electron concentration ns∼6.8×1013 cm−2.

n -type doping characteristics of O-implanted GaN

“…As for ion-implantation doping of GaN, several n-and p-type implantation techniques have already been reported with the use of Si 6,8,9,[13][14][15][16][17][18][19][20] being the most common dopant for n-type, and Be 21-24 and Mg 8,9,13,22,25 the main elements implanted for p-type doping. The combination of n-and p-type implantation-doping techniques is expected to be a powerful tool for fabricating smart electronic devices such as a power switch.…”

Electrical and optical activation studies of Si-implanted GaN

“…This is particularly true for GaN implanted with the acceptor or donor species at lower doses (Ͻ10 15 cm Ϫ2 ). Eiting et al 8 reported only 17% electrical activation efficiency for the GaN implanted with Si at a dose of 4 ϫ 10 14 cm Ϫ2 with 100 keV after annealing at 1150°C for 5 min. Molnar et al 4 implanted a total dose of 4.4 ϫ 10 14 cm Ϫ2 Si ions with multiple energies, annealed at 1150°C for 2 min, and obtained only 1% donor activation, assuming a donor ionization energy of 26 meV.…”

n + - GaN formed by Si implantation into p-GaN

“…Previous reports have shown that Si ϩ implants can be efficiently activated in n-type GaN by N 2 -ambient annealing at temperatures у1000°C. [5][6][7][8] In this study, n ϩ -GaN films were formed by multiple 28 Si ϩ implantation into p-type GaN. After implantation, samples were thermal annealed in N 2 ambient.…”