Fig. 1. Schematic of experimental procedure
Fig. 2. Curves of transmissivity and reflectivity of 4H-SiC
Fig. 3. EDS patterns on surface of samples before and after Al doping. (a) Undoped 4H-SiC;(b) 4H-SiC with a Al film thickness of 240 nm
Fig. 4. Resistance tests. (a) Schematic; (b) I-V curves between electrodes 1 and 2;(c) I-V curve between electrodes 3 and 4
Fig. 5. Ohmic contact versus Al film thickness and number of laser pulses
Fig. 6. Optical micrographs and surface roughness of 4H-SiC under different numbers of laser pulses.(a) 1, micrograph; (b) 50, micrograph; (c) 1, roughness; (d) 50, roughness
Fig. 7. Resistivity and carrier concentration versus number of laser pulses. (a) Bulk resistivity;(b) bulk carrier concentration
Fig. 8. Hall test results of laser irradiated 4H-SiC when Al film thickness is 120 nm and number of laser pulses is 50. (a) I-V curves between electrodes 1 and 2; (b) I-V curves between electrodes 1 and 2
Fig. 9. XPS spectra on surface of 4H-SiC before and after Al doping
Fig. 10. XPS spectra on surface of 4H-SiC before and after Al doping. (a) Si 2p orbit; (b) C 1s orbit; (c) Al 2p orbit
Number oflaser pulses | Atomic fraction /% |
---|
Si | Al | O |
---|
0 | 100 | 0 | 0 | 1 | 82.26 | 1.34 | 16.40 | 5 | 79.41 | 2.33 | 18.26 | 10 | 80.18 | 4.40 | 15.42 | 50 | 78.64 | 4.9 | 16.46 |
|
Table 1. Surface element contents of laser irradiated 4H-SiC with a Al film thickness of 240 nm