Electrical and optical activation studies of Si-implanted GaN

Abstract

Comprehensive and systematic electrical and optical activation studies of Siimplanted GaN were made as a function of ion dose and anneal temperature. Silicon ions were implanted at 200 keV with doses ranging from 1 ϫ 10 13 cm Ϫ2 to 5 ϫ 10 15 cm Ϫ2 at room temperature. The samples were proximity-cap annealed from 1050°C to 1350°C with a 500-Å-thick AlN cap in a nitrogen environment. The optimum anneal temperature for high dose implanted samples is approximately 1350°C, exhibiting nearly 100% electrical activation efficiency. For low dose (Յ5 ϫ 10 14 cm Ϫ2 ) samples, the electrical activation efficiencies continue to increase with an anneal temperature through 1350°C. Consistent with the electrical results, the photoluminescence (PL) measurements show excellent implantation damage recovery after annealing the samples at 1350°C for 20 sec, exhibiting a sharp neutral-donor-bound exciton peak along with a sharp donoracceptor pair peak. The mobilities increase with anneal temperature, and the highest mobility obtained is 250 cm 2 /Vs. The results also indicate that the AlN cap protected the implanted GaN layer during high-temperature annealing without creating significant anneal-induced damage.

Temperature-Dependent Studies of Si-Implanted Al0.33Ga0.67N with Different Annealing Temperatures and Times

“…The lack of electrical activation after annealing at 1150°C is also apparent in the mobility data for the samples implanted with the lowest Si dose of 1 9 10 14 cm À2 , showing only 21 cm 2 /V s. This mobility value is lower than those for the higherdose-implanted samples, and also those measured for GaN and Al x Ga 1Àx N with lower Al mole fraction. [3][4][5]19 This indicates that this annealing temperature is too low to sufficiently activate implanted ions and/or to repair lattice damage during annealing. However, the samples for this lowest dose of 1 9 10 14 cm À2 show much higher mobilities than the other high-dose samples after annealing at 1200°C or higher because both impurity and defect scattering are less for this dose due to the relatively smaller number of impurities and the smaller amount of residual damage.…”

Electrical and optical characterization studies of lower dose Si-implanted AlxGa1−xN

“…However, in order to make the implanted ions optically and electrically active, it is required to anneal out the implantation damage-related defects without dissociation of host atoms. Previous studies have shown that the activation of implanted impurities in III-nitride materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] is much more difficult than for conventional compound semiconductors such as GaAs and InP. A number of articles 1-8 and reviews 9-10 reporting on ion implantation studies in GaN have been published.…”

“…Cao et al 6 reported electrical activation efficiency as high as 90% for GaN implanted with 100 keV Si ions at a dose of 5 3 10 15 cm ÿ2 and annealed at 1,400°C for 10 sec. Fellows et al 7,8 reported a 100% electrical activation for GaN implanted with Si at high doses (!1 3 10 15 cm ÿ2 ) and annealed at 1,350°C. However, they reported lower activation efficiencies for low dose ( 5 3 10 14 cm ÿ2 ) implanted samples, and efficiencies increased with anneal temperature even after annealing at 1,350°C.…”

Implantation damage recovery and carrier activation studies of Si‐implanted Al0.18Ga0.82N by temperature dependent Hall‐effect measurements

“…Also, H-, He-, or N-ion implantation has been used in device isolation to compensate effectively both p-and ntype GaN [1][2][3][4]. Although significant progress has been reported for ion implantation doping and annealing of GaN and AlGaN, there are still many areas to be further investigated [5][6][7][8][9]. Implantation damage created in III-nitrides is very difficult to remove, making it hard to electrically activate the implanted ions.…”

“…Implantation damage created in III-nitrides is very difficult to remove, making it hard to electrically activate the implanted ions. Most of the reported studies have indicated that an anneal temperature of 1200 o C or higher for short anneal time periods is required to repair the damage from implantation [5][6][7][8]. Cao et al [5] , respectively, after annealing at 1350 o C for 2 min.…”