PD-aSi-2026-007 a-Si:H photodetector — temporal response and responsivity analysis
Identity Sample ID PD-aSi-2026-007 Title a-Si:H photodetector — temporal response and responsivity analysis Status Completed Operator Dr. N. Şahin Laboratory / Facility Optoelectronic Characterization Lab
Substrate / Material Substrate Material ITO-coated glass Active Layer Material Hydrogenated amorphous silicon (a-Si:H) p-i-n
Notes Tags analysis, photodetector, responsivity, EQE, 3dB bandwidth Notes Raw data processed with the application's Analysis module; metrics in the Result card below.
Process Steps Light/dark I-V + temporal response (Measurement Binding) Instrument Keithley 2450 SMU + 530 nm LED (pulsed) Calibration Status Valid Uncertainty (±) ±0.3% I Caption At −2 V reverse bias; LED 1 kHz square wave. Rise/fall and photo/dark ratio extracted.
Dark current ≈ 1.2 nA @ −2 V. Illuminated (1 mW/cm²) ≈ 38 µA.
Spectral responsivity (UV-Vis) (Spectroscopy) Technique UV-Vis Instrument Ocean Optics HR4000 + monochromator Range 350–800 nm Resolution 2 nm Peaks / Bands Peak responsivity ≈ 560 nm; band edge ≈ 720 nm (Eg≈1.72 eV). Assignment / Interpretation Consistent with the a-Si:H optical band gap; ITO/p-layer absorption in the blue region.
Response-time statistics (10 measurements) (Statistics / Data Summary) N (sample count) 10 Mean 18.4 µs (rise) / 22.1 µs (fall) Std. Deviation 1.2 µs / 1.5 µs CV (%) 6.5% / 6.8% Min 16.9 µs Max 20.3 µs Method / Software MikroFab Analysis — Temporal Response module (10–90% threshold)
Extracted photodetector metrics (vs target) (Result (Spec)) Parameter Value Uncertainty (±) Unit Specification Pass Responsivity (R) @560 nm 0.31 0.02 A/W ≥0.25 ✓ External quantum efficiency (EQE) 68 3 % ≥60 ✓ 3 dB bandwidth 19.3 0.8 kHz ≥15 ✓ Photo/dark ratio 3.2e4 — ≥1e4 ✓ NEP 4.1e-13 W/√Hz ≤1e-12 ✓
All metrics passed specification. The device is suitable for 530 nm visible-light detection.
Interpretation / next step (Free Note) Bandwidth is limited by carrier transit time; reducing the i-layer thickness 500→350 nm should increase bandwidth ~2× (at the cost of a slight drop in responsivity). Let's try it in the next lot.