Selective area isolation of β-Ga2O3 using multiple energy nitrogen ion implantation

Abstract

In this study, we report on the application of multiple energy nitrogen ion implantation for the electrical isolation of electronic devices on monoclinic β-Ga2O3. By the introduction of uniformly distributed midgap damage-related levels in the Ga2O3 crystal lattice, we are able to increase the sheet resistances by more than 9 orders of magnitude to ≥1013 Ω/sq which remains stable up to annealing temperatures of 600 °C carried out for 60 s under a nitrogen atmosphere. At higher annealing temperatures, the damage-related trap levels are being removed causing a significant drop of the sheet resistance down to 4 × 105 Ω/sq for annealing temperatures of 800 °C. This effect is preceded by a structural recovery of the implantation damages via the recrystallization of the crystal lattice at already 400 °C as verified by x-ray diffraction measurements. The extracted activation energies of the deep states controlling the high resistivity of Ga2O3 after implantation are in the range of 0.7 eV, showing a strong correlation with the annealing temperature dependence of the sheet resistance and thus supporting the theory of a damage-induced isolation mechanism.

Monte‐Carlo‐based simulation study of ion‐implantation in gallium oxide devices

“…To understand and analyse the damage, vacancy generation and various energy losses two different ions (Mg and N) are bombarded with same energy on the gallium oxide target. The simulation is calibrated with the help of Tetzner et al, 18 fabricated data that use nitrogen multiple ion implantation for the isolation of gallium oxide‐based devices. The simulation calibration graph with reference to experimental data is shown here in Figure 3.…”

“…So for gallium oxide, nitrogen and magnesium are found to be deep acceptors. Some experimental work also has been carried out for isolation of gallium oxide based devices using Mg and N. Some gallium oxide‐based lateral devices are demonstrated with nitrogen implantation for inter‐device isolation and current blocking layers for vertical devices as well 18–21 . For better understanding the physics behind the ionization, energy losses and damages during the implantation process must be understood.…”

“…Some experimental work also has been carried out for isolation of gallium oxide based devices using Mg and N. Some gallium oxide-based lateral devices are demonstrated with nitrogen implantation for inter-device isolation and current blocking layers for vertical devices as well. [18][19][20][21] For better understanding the physics behind the ionization, energy losses and damages during the implantation process must be understood. This paper comprehensively describes the analysis of ion-implantation of Mg and N for implantation isolation in target layer of gallium oxide by Monte Carlo simulations using SRIM software.…”

Impact of electron irradiation on semi-insulating and conductive β-Ga2O3 single crystals

“…For instance, the sheet resistance of Si-doped b-Ga 2 O 3 single crystal increased by more than nine orders of magnitude after N + irradiation. 14 Although radiation defects depend on the type of incident particles, the aforementioned work shows that radiation defects capture free carriers, degrade carrier mobility, form gap states that pin Fermi levels, and form trapping states that initiate breakdown. 17 While these results promoted a step forward in understanding the radiation-damage behavior, most of the investigated b-Ga 2 O 3 crystals/substrates possess a high electron density (above 1 Â 10 16 cm À3 ) and are conductive.…”

Ion implantation in β-Ga2O3: Physics and technology

“…In the case of ion implantation, defects such as gallium vacancies can also have a compensating effect 15 10 . In the work 57 , nitrogen ions were implanted into epitaxial β-Ga 2 O 3 layers with an initial electron concentration of 2×10 18 cm -3 , and a box-like profile of generated vacancies with a concentration of ~ 10 21 cm -3 was created. Measurements of the layer conductivity and the Hall effect of the N + irradiated samples demonstrate formation of a semi-insulating layer, the resistivity of which remains practically unchanged up to T ann = 600 °C.…”