Dummy Au Devices on SiC Ed Cazalas 4/2/13

Ch9,12 (b) – Backgate sweep – Light (lamp)

Ch9,12 (b) – Backgate sweep – Dark

Ch2,3 (a) – Alpha exposure – Dark

Ch9,12 (b) – Light exposure, BG = -20V

Ch9,12 (b) – Light exposure, BG = -5V

Ch9,12 (b) – Light exposure, BG = +5V

Ch9,12 (b) – Light exposure, BG = +20V

Ch2,3 (a) – Alpha exposure – Dark BG = +40V BG = +20V BG = -20V BG = -40V

Au Dummy Device Pin Configuration (Total Area = 720 μm 2 ) Ch 2, 3 vs. 3, 14 Compare channel used vs. leakage current

Alpha exposure – Dark BG = -40V BG = +40V BG = +20V BG = -20V dI ≈ 0.2 nAdI ≈ 0.25 nA dI ≈ 0.15 nA dI ≈ 0.25 nA

Alpha exposure – Dark Alpha (red), device A device A device A + B (all tests) device B

Alpha exposure – Calculate # of Alphas 0.2 nA 0.2 nC/s * 6.24E18 e-/C = 1.25E9 e-/s Band gap (SiC) ≈ 3 eV/ip 1.25E9 e-/s * 3 ev/ip = 3.7E9 eV/s Assume E α = 3 MeV = 3E6 eV/α (3.7E9 eV/s) / (3E6 eV/α) ≈ 1200 α/s Alpha Activity = A 0 (Area of Irradiation / Source Area) where A 0 = 3.7E5 Bq Source Area = 2.83E-5 m 2 Area of Irradiation = Area of Au = 720 μm 2 = 7.2E-10 m 2 Alpha Activity = 9.4 α/s <- too small Area of Irradiation = mm 2 = 0.3 mm on a side

Observations: No field effect on dummy device in light or dark Exposure to light or alpha does not change Au resistance Exposure to light or alpha does cause increase in leakage current on some channels. All “A” device channels show backgate leakage response (fast) Only some “B” device channels show backgate leakage response (slow) Importantly, alpha “step response” not observed, which discounts ionization collection