Ion implantation in GaN at liquid-nitrogen temperature: Structural characteristics and amorphization

Liu, C.; Mensching, B.; Zeitler, M.; Volz, Kerstin; Rauschenbach, B.

doi:10.1103/physrevb.57.2530

Cited by 125 publications

(58 citation statements)

References 24 publications

(29 reference statements)

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“…6͑a͒ that the damage buildup in GaN is highly sigmodal for the case of light ion bombardment. This behavior is consistent with the results of LN 2 temperature bombardment of GaN with intermediate mass ions ͓Si, 2 Ar, 6 and Ca ͑Ref. 6͔͒.…”

Section: A Bombardment With 40 Kev C Ionssupporting

confidence: 80%

“…[2][3][4][5][6][7][8][9] This situation is surprising since such studies often give an insight into the important properties of the defects produced by an ion beam. For example, information on the mobility and effective lifetimes of defects, defect clustering efficiency, and on the influence of interfaces on mobile defects can often be obtained from an analysis of damage buildup under ion irradiation.…”

Section: Introductionmentioning

confidence: 98%

“…Detailed studies of amorphization behavior with increasing ion dose have been reported only for bombardment of GaN with Si, 2 Ar, 6 and Ca ͑Ref. 6͒ ions at liquid nitrogen (LN 2 ) temperature.…”

Section: Introductionmentioning

confidence: 99%

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Damage buildup in GaN under ion bombardment

et al. 2000

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The damage buildup until amorphization in wurtzite GaN films under keV light ( 12 C) and heavy ( 197 Au) ion bombardment at room and liquid nitrogen (LN 2 ) temperatures is studied by Rutherford backscattering/ channeling ͑RBS/C͒ spectrometry and transmission electron microscopy ͑TEM͒. The effect of beam flux on implantation damage in GaN is reported. A marked similarity between damage buildup for light and heavy ion bombardment regimes is observed. The results point to substantial dynamic annealing of irradiation defects even during heavy ion bombardment at LN 2 temperature. Amorphization starts from the GaN surface with increasing ion dose for both LN 2 and room-temperature bombardment with light or heavy ions. A strong surface defect peak, seen by RBS/C, arises from an amorphous layer at the GaN surface, as indicated by TEM. The origin of such an amorphous layer is attributed to the trapping of mobile point defects by the GaN surface, as suggested by the flux behavior. However, in the samples implanted with light ions to low doses (1 ϫ10 15 cm Ϫ2 ͒, no amorphous layer on the GaN surface is revealed by TEM. Damage buildup is highly sigmodal for LN 2 temperature irradiation with light or heavy ions. Formation of planar defects in the crystal bulk is assumed to provide a ''nucleation site'' for amorphization with increasing ion dose during irradiation at LN 2 temperature. For room-temperature bombardment with heavy ions, the damage in the GaN bulk region saturates at a level lower than that of the amorphous phase, as measured by RBS/C, and amorphization proceeds from the GaN surface with increasing ion dose. For such a saturation regime at room temperature, implantation damage in the bulk consists of point-defect clusters and planar defects which are parallel to the basal plane of the GaN film. Various defect interaction processes in GaN during ion bombardment are proposed to explain the observed, somewhat unexpected behavior of disorder buildup.

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Section: A Bombardment With 40 Kev C Ionssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 98%

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Damage buildup in GaN under ion bombardment

et al. 2000

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“…Recent ion-implantation studies [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] have revealed that, unlike the situation for mature semiconductors such as Si and GaAs, GaN exhibits a range of intriguing behavior involving extreme property changes under ion bombardment. 19 In particular, it has been shown that dynamic annealing processes ͑i.e., defect-interaction processes͒ in GaN are extremely efficient even during heavy-ion bombardment at liquid-nitrogen temperature.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2001

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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.

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“…For the as-implanted GaN, early studies [5][6][7] have reported on some typical features: planar defects, and an amorphous layer which formed on top of GaN. The planar defects have been observed to be the most characteristic defects in GaN bombarded with ions in a wide range of implantation conditions, independently of the ion, fluence, energy, and implantation temperature.…”

Section: Introductionmentioning

confidence: 99%

Rare Earth Ion Implantation in GaN: Damage Formation and Recovery

et al. 2006

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Rare earth ions implanted GaN has been investigated by transmission electron microscopy versus the fluence, using Er, Eu or Tm ions at 150 keV or 300 keV and at room temperature. Point defect clusters and stacking faults are generated from low fluences (7 × 10 13 at/cm 2 ), their density increases with the fluence up to the formation of a highly disordered layer at the surface. This highly disordered layer is observed from a threshold fluence of 3×10 14 at/cm 2 at 150 keV and 3×10 15 at/cm 2 at 300 keV, and appears to be composed of voids and misoriented nanocrystallites. Its thickness rapidly increases with the fluence, and then saturates. Both basal and prismatic stacking faults were observed. Basal stacking faults are I 1 in majority, but E or I2 have also been identified. I1 basal stacking faults propagate easily through GaN by folding from basal to prismatic planes. Channelling implantation, increasing the implantation temperature from room temperature to 500 • C, or implanting through a 10 nm thick AlN cap reduce the crystallographic damage, particularly by retarding the formation of the highly disordered layer. Implanting through the AlN cap allows the highly disordered layer formation threshold fluence to be increased by one order of magnitude, as well as the annealing at high temperature (1300 • C) which brings about a strong optical activation of the rare earths.

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Ion implantation in GaN at liquid-nitrogen temperature: Structural characteristics and amorphization

Cited by 125 publications

References 24 publications

Damage buildup in GaN under ion bombardment

Damage buildup in GaN under ion bombardment

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

Rare Earth Ion Implantation in GaN: Damage Formation and Recovery

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