Fig. 1. Schematic diagram of SPDR operating at frequency of approximately 4.8 GHz. Fig. 2. Schematic diagram of SiPDR operating at frequency of about 10.8 GHz. Fig. 3. Photograph of SiPDR (in front) and 4.8-GHz SPDRs used in experi- ments presented in this paper. Fig. 4. Computed resonant-frequency shifts and @-factors due to conductor losses in the sample (Qs) in SiPDR, as shown in Fig. 2, with L = 2.3 mm. Computations have been performed for ¢,, = 11.65 (Silicon) assuming negli- gible dielectric losses in the sample. Fig. 5. Computed resonant-frequency shifts and @-factors due to conductor losses in the sample (Q;) for SiPDR, as shown in Fig. 2, with L = 4.3 mm. Computations have been performed for ¢, = 11.65 (Silicon) assuming negli- gible dielectric losses in the sample. RESULTS OF MEASUREMENTS OF GaAs WAFERS RESULTS OF MEASUREMENTS OF SiC WAFERS (when the slope of Q-factor versus conductivity is negative). while the @-factor uncertainties become dominant for lower resistivity samples (when the slo pe of (Q-factor versus con- ductivity is positive). Small sensitivity of the Q-factor on the sample thicknesses for low-resistivity samples is due to skin- depth smaller that the thickness of of absolute resistivity determinat: the sample. Overall errors ion for well-machined flat samples (machined to within 0.5% tolerance of thickness) are approximately 2%—4% for both Si PDR and SPDR techniques. For high-resistivity samples, the permittivity can be determined with uncertainty of approximately 0.5%. RESULTS OF MEASUREMENTS OF 6/ HR- SILICON WAFERS (TOPSIL) Fig. 6. Measured resistivity versus temperature employing SiPDR for sample no. 5 (Table I). Theoretical resistivity values have been evaluated assuming a dopand concentration Ng of 1.85 x 10!4 (cm~3) and electron mobility Ve of 1430(T/300)~?-?. Fig. 7. Resistivity mapping employing SPDR on P21000 wafer. Numbers on lines denote resistivity in ohm centimeters. Fig. 8. Measured dielectric-loss tangent of GaAs sample no. 2214 versus frequency and versus temperature (at frequency of approximately 4.7 GHz).
