Effect of ion species on the accumulation of ion-beam damage inGaN

Abstract

Wurtzite GaN epilayers bombarded with a wide range of ion species ͑10 keV 1 H, 40 keV 12 C, 50 keV 16 O, 600 keV 28 Si, 130 keV 63 Cu, 200 keV 107 Ag, 300 keV 197 Au, and 500 keV 209 Bi) are studied by a combination of Rutherford backscattering/channeling ͑RBS/C͒ spectrometry and cross-sectional transmission electron microscopy. Results show that strong dynamic annealing processes lead to a complex dependence of the damage-buildup behavior in GaN on ion species. For room-temperature bombardment with different ion species, bulk disorder, as measured by RBS/C, saturates at some level that is below the random level, and amorphization proceeds layer-by-layer from the GaN surface with increasing ion dose. The saturation level of bulk disorder depends on implant conditions and is much higher for light-ion bombardment than for the heavy-ion irradiation regime. In the case of light ions, when ion doses needed to observe significant lattice disorder in GaN are large (տ10 16 cm Ϫ2 ), chemical effects of implanted species dominate. Such implanted atoms appear to stabilize an amorphous phase in GaN and/or to act as effective traps for ion-beam-generated mobile point defects and enhance damage buildup. In particular, the presence of a large conce ntration of carbon in GaN strongly enhances the accumulation of implantation-produced disorder. For heavier ions, where chemical effects of implanted species seem to be negligible, an increase in the density of collision cascades strongly increases the level of implantation-produced lattice disorder in the bulk as well as the rate of layerby-layer amorphization proceeding from the surface. Such an increase in stable damage and the rate of planar amorphization is attributed to ͑i͒ an increase in the defect clustering efficiency with increasing density of ion-beam-generated defects and/or ͑ii͒ a superlinear dependence of ion-beam-generated defects, which survive cascade quenching, on the density of collision cascades. Physical mechanisms responsible for such a superlinear dependence of ion-beam-generated defects on collision cascade density are considered. Mechanisms of surface and bulk amorphization in GaN are also discussed.

Indium implantation and annealing of GaN: Lattice damage and recovery

“…However, the damage profile extends at larger depth compared to the distribution of the implanted ions. Both characteristics are consistent with the strong dynamic annealing of GaN during ion implantation with either heavy or light elements [18,19]. The evolution of the maximum defect concentration on the ion fluence is shown in Fig.…”

Doping of Ga2O3bulk crystals and NWs by ion implantation

“…This pronounced surface damage is unusual since the maximum nuclear energy deposition, which is assumed to be the main source for implantation damage in the present energy regime, has its maximum deeper inside the sample (at ~34 nm depth according to SRIM2013 23 Monte Carlo simulations). Very similar behavior has been found for ion implantation in GaN and its origin is still under debate 24,25,26 .…”

Effects of ion implantation on yellow luminescence in unintentional doped n-type GaN

“…Although very efficient dynamic annealing processes in GaN during ion bombardment have been found, such dynamic annealing is never perfect [3]. Ion implantation inevitably produces lattice defects in GaN, and most of the implantation-produced defects act as efficient nonradiative recombination centers, which result in a strong decrease in the YL intensity.…”

“…Moreover, Kucheyev et al [3] found that during ion implantation with various energies and doses, the surface is a preferential trapping site for mobile defects in GaN and act as a strong sink for the accumulation of migrating point defects. As discussed above, the YL of GaN is associated with V G and V G complexes as well as C or C complexes, while the NBE emission is simply ascribed to a band to band recombination in Ref.…”

“…However, post-annealing is necessary for the activation of the dopants and for the recovery of the lattice damage produced by the energetic ions. Compared with other mature semiconductors (such as Si and GaAs), GaN shows strong dynamic annealing even during heavy-ion bombardment at liquid-nitrogen temperature, and it is very difficult to be amorphized [3,4]. In this letter, we discuss the influences of ion implantation and post-annealing on YL of GaN by photoluminescence (PL) measurements.…”