Martin S. Janson

Transient enhanced diffusion of implanted boron in 4H-silicon carbide

Experimental evidence is given for transient enhanced diffusion of boron (B) in ion-implanted silicon carbide (SiC). The implanted B is diffusing several mu m into the samples when annealed at 1600 ...

Hydrogen passivation of silicon carbide by low-energy ion implantation

Ion implantation of deuterium is performed to investigate the mobility and passivating effect of hydrogen in epitaxial α-SiC (polytypes 4H and 6H). To avoid excessive damage and the resulting trapping of hydrogen, the implantation is performed with low energy (600 eV 2H2+). The 2H depth profile is analyzed by secondary ion mass spectrometry. Electrical properties are measured by capacitance–voltage profiling and admittance spectroscopy. In p-type SiC, hydrogen diffuses on a μm scale even at room temperature and effectively passivates acceptors. In n-type SiC, the incorporation of H is suppressed and no passivation is detected.

On the nature of ion implantation induced dislocation loops in 4H-silicon carbide

Transmission electron microscopy was used to investigate 11B, 12C, 14N, 27Al, 28Si, and 37Ar ion-implanted 4H-SiC epilayers and subsequent defect formation after high temperature annealing. During the annealing process extrinsic dislocation loops of interstitial type are formed on the SiC basal plane with a depth distribution roughly corresponding to the distribution of the implanted ions. The investigation reveals that in samples where the implanted ions are substituting for a position in the silicon sublattice, generating an excess of interstitial silicon, the dislocation loops are more readily formed than in a sample implanted with an ion substituting for carbon.

Solubility limit and precipitate formation in Al-doped 4H-SiC epitaxial material

Heavily Al-doped 4H-SiC structures have been prepared by vapor phase epitaxy. Subsequent anneals have been carried out in an Ar atmosphere in a rf-heated furnace between 1500 degreesC and 2000 degr ...

Ion implantation of silicon carbide

Ion implantation is an important technique for a successful implementation of commercial SiC devices. Much effort has also been devoted to optimising implantation and annealing parameters to improve the electrical device characteristics. However, there is a severe lack of understanding of the fundamental implantation process and the generation and annealing kinetics of point defects and defect complexes. Only very few of the most elementary intrinsic point defects have been unambiguously identified so far. To reach a deeper understanding of the basic mechanisms SiC samples have been implanted with a broad range of ions, energies, doses, etc., and the resulting defects and damage produced in the lattice have been studied with a multitude of characterisation techniques. In this contribution we will review some of the results generated recently and also try to indicate where more research is needed. In particular, deep level transient spectroscopy (DLTS) has been used to investigate point defects at very low doses and transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) are used for studying the damage build-up at high doses.

Ion implantation range distributions in silicon carbide

The first to fourth order distribution moments, Rp, ΔRp, γ, and β, of 152 single energy 1H, 2H, 7Li, 11B, 14N, 16O, 27Al, 31P, 69Ga, and 75As implantations into silicon carbide (SiC) have been assembled. Fifty of these implantations have been performed and analyzed in the present study while the remaining implantation data was compiled from the literature. For ions with a limited amount of experimental data, additional implantations were simulated using a recently developed binary collision approximation code for crystalline materials. Least squares fits of analytical functions to the distribution moments versus implantation energy provide the base for an empirical ion implantation simulator using Pearson frequency functions.

Effect of crystal orientation on the implant profile of 60 keV Al into 4H-SiC crystals

The authors acknowledge the STINT ~Swedish Foundation for international cooperation in research and higher education! program and Australian Research Council for support under the Discovery grant and fellowship program.

Fluence, flux, and implantation temperature dependence of ion-implantation-induced defect production in 4H-SiC

This work has been supported partly by the Nordic Academy for Education and Research Training (NorFa) and the Swedish Foundation for International cooperation in Research and Higher Education (STINT).

Solubility limits of dopants in 4H-SiC

Epitaxial 4H-SiC structures with heavily boron or aluminium doped layers have been prepared by vapour phase epitaxy. The samples have been annealed in Ar atmosphere in an RF-heated furnace between 1700 and 2000 C for 45 min to 64 h. Secondary ion mass spectrometry has been employed to obtain depth distributions as well as lateral distributions (ion imaging) for boron and aluminium. Transmission electron microscopy has been used to study the crystallinity and determine phase composition. Solubility limits of ∼ 1 × 10 20 Al/cm 3 (1700°C) and < 1 × 10 20 B/cm 3 (1900°C) have been deduced.

Self-diffusion of 12C and 13C in intrinsic 4H–SiC

Self-diffusion of carbon (12C and 13C) in low-doped (intrinsic) 4H–SiC has been studied using secondary ion mass spectrometry. A two layer 13C enriched structure with 13C/12C ratios of 0.01 and 0.1, respectively, have been prepared by vapor phase epitaxy. Subsequent anneals have been carried out in Ar atmosphere in a rf heated furnace between 2100 and 2350 °C for 15 min–40 h. The 13C depth profiles reveal a strict t evolution for the diffusion, and the extracted carbon self-diffusion coefficients closely follow an Arrhenius temperature dependence: D*=8.4×102 exp(−8.50 eV/kT) cm2/s. The extracted D* are found to be 5 orders of magnitude lower than previously reported for the same temperatures in 14C radio-tracer experiments.