Electrical isolation of GaN by ion implantation damage: Experiment and model

Abstract

Electrical and optical isolation of unintentionally doped GaN layers due to the damage created by H+ and He+ ions passing through the layer are demonstrated. As a result of the irradiation, the sample resistance increases by 11 orders of magnitude and the band-to-band photoluminescence (PL) emission is totally quenched. Following annealing (1000 °C, 30 s), the conductivity can be nearly completely recovered, whereas only partial recovery of the PL emission is obtained. A model is proposed which invokes the presence of potential barriers for electronic transport across extended defects as the major factor limiting carrier mobility. Radiation defects increase these barriers, thus affecting the sample resistivity. This model fits the experimental results for both H and He induced damage extremely well and thus proves that defects created by nuclear collisions of the ions traversing the layer are responsible for the observed effects.

Influence of dual-frequency plasma-enhanced chemical-vapor deposition Si3N4 passivation on the electrical characteristics of AlGaN/GaN heterostructure field-effect transistors

“…Nevertheless, the concept remains similar. For instance, Uzan-Saguy et al 28 reported an increase of 11 orders of magnitude in the resistivity of GaN upon 320-keV H ϩ ion-implantation damage. Heavy ion bombardment is also shown to result in the structural damage of GaN films, 29 and this may account for the sharp decrease in the mobility of the dual-frequency samples in Fig.…”

The Effect of Grain Boundaries on Electrical Conductivity in Thin GaN Layers

“…Since f gb $ 1aN D it is possible to increase f gb by ion implantation induced damage. The compensating effect of radiation damage is to produce an effective doping concentration N DY eff N D À aD, where D is the implantation dose and a is the number of electrically active implantation induced defects, per ion traversing the thin film [12]. The sample resistivity of an implanted sample is predicted to be drastically changed with the implantation dose.…”

Model for electrical isolation of GaN by light-ion bombardment

“…This process can be used for electrical isolation of closely spaced devices. [2][3][4][5][6][7][8][9][10] Indeed, several previous reports have demonstrated that the resistance of GaN films can be increased by ϳ10 orders of magnitude as a result of lattice defects produced by ion irradiation, and such electrical isolation has excellent thermal stability. 4 -10 The mechanism of electrical isolation of semiconductors by ion-irradiation-produced defects has been attributed to ͑i͒ defect-induced degradation of carrier mobility and ͑ii͒ the trapping of free carriers at deep levels associated with ionbeam-produced defects.…”

“…The only model for electrical isolation of GaN that we are aware of has been reported in Ref. 7. However, this model 7 is based on a somewhat speculative assumption that ionimplanted GaN can be considered as a polycrystalline material.…”