Properties of secondary ions in ion beam sputtering of Ga2O3

Abstract

The energy distributions of secondary ions for the ion beam sputtering of a Ga2O3 target using O2+ and Ar+ ions are measured in dependence on various process parameters using energy-selective mass spectrometry. The process parameters include sputtering geometry (ion incidence angle α, polar emission angle β, scattering angle γ), the energy of incident ions Eion, and the background pressure of O2. The main secondary ion species are identified to be Ga+, O+, O2+, and, when argon is used as a process gas, Ar+. The changes in the sputtering geometry and the primary ion energy have the most impact on the energy distributions of secondary Ga+ and O+ ions, giving control over the high-energy tail, which is attributed to anisotropy effects in sputtering. The formation of O2+ ions is attributed to collisions with background gas molecules, as their energy distributions are not influenced by the sputtering geometry or the primary ion energy. The increase of the O2 pressure leads to a minor decrease of the energy of Ga+ ions due to collisions with the background gas particles. The use of primary Ar+ ions with O2 background pressure does not show any specific effect on energy distributions of Ga+, O+, and O2+ ions except for the case without additional O2 background. In the latter case, much fewer O+ and O2+ ions are produced indicative of oxygen depletion of the surface due to preferential sputtering of oxygen. At all considered O2 pressures, the energy distributions of Ar+ ions have a high-energy peak, attributed to direct scattering events. The trends in experimental data show qualitative agreement to simulations using the Monte Carlo code SDTrimSP.

β-Ga2O3 Schottky Barrier Diode with Ion Beam Sputter-Deposited Semi-Insulating Layer

“…The IBS-Ga 2 O 3 film, which is in contact with the Ni anode, is polycrystalline and, as shown below, is semi-insulating. We believe this is due to the nature of the film deposition process [51][52][53]. It is worth noting that such relatively thick β-Ga 2 O 3 films deposited via the IBS method on UID β-Ga 2 O 3 substrates and annealed at the conditions described above are being studied for the first time.…”

“…According to Refs. [51][52][53], it was expected that IBS β-Ga 2 O 3 films would be monocrystalline and of high structural quality.…”

“…IBS deposition is characterized by the highest energies of the particles involved in the formation of thin films, as well as a large number of parameters affecting the sputtering process and the ability to achieve a higher vacuum in the operating mode [50][51][52][53]. This allows a more subtle variation in the electrically conductive, structural, optical, mechanical and other properties of the films during the deposition process and allows us to obtain more homogeneous layers in terms of thickness and composition over larger areas of the substrates.…”

Ga+ Focused Ion Beam Damage in n-type Ga2O3 and Its Recovery after Annealing Treatment

“…This technique is now being applied to the ultra-wide bandgap semiconductor Ga 2 O 3 , which h is attracting interest for power electronics and solar-blind UV detectors (6)(7)(8)(9)(10). Kalanov et al (11) reported that the main secondary ions for the ion beam sputtering of Ga 2 O 3 using O + and Ar+ ions are Ga+, O+ and O2+. There is little known about the effect of FIB on the electrical and structural properties of Ga 2 O 3 , which must be rectified as this technique is integrated into process schemes for devices or TEM sample preparation.…”

Sidewall Electrical Damage in β-Ga2O3 Rectifiers Exposed to Ga+ Focused Ion Beams

“…A wide variety of Ga 2 O 3 devices with promising performance have been reported. [8][9][10][11][12][13][14][15][16] In both vertical rectifiers and lateral transistor structures, the presence of residual ion beam damage after mesa isolation or milling to create fins or trenches will be detrimental to device performance, [8][9][10][11][12][13][14][15][16][17] through inducing additional leakage current or creating additional parasitics. While ion-enhanced diffusion [18][19][20][21] of point defects created on horizontal semiconductor surfaces is known to produce damage depths well beyond those expected from ion range simulations, 22,23 there is limited understanding of the damage produced on a mesa sidewall in β-Ga 2 O 3 .…”