1：Experimental Design and Method Selection:

The study involves fabricating a photodiode using n-SnSe2 on p-Si substrate to exploit the high mobility of p-Si for improved response times. Theoretical models for transit time in photodiodes and photoconductors are used.

2：Sample Selection and Data Sources:

p-Si (100) substrate with resistivity ~2 Ωcm (carrier concentration ~7×10^15 cm^-3) from Sigma Aldrich is used. SnSe2 thin films are grown via DC sputtering and selenization.

3：List of Experimental Equipment and Materials:

Equipment includes DC magnetron sputtering system, selenization chamber, X-ray diffractometer (X'pert-PRO PANAlytical), SEM (Ultra55 FE-SEM Karl Zeiss EDS), AFM (A.P.E. Research A100-AFM), surface profilometer (Veeco Dektak 6M), UV-Vis-NIR spectrophotometer (Perkin Elmer-lambda 750), Raman spectrometer (Visible LabRAM HR), XPS (Axis Ultra DLD from Kratos), thermal evaporation system for Cr/Au electrodes, Keithley SMU2400 source meter, 1064 nm laser, mechanical optical chopper, digital storage oscilloscope. Materials include Sn metal target, hydrofluoric acid, deionized water, Ar gas, Cr and Au for electrodes.

4：Experimental Procedures and Operational Workflow:

p-Si substrate is etched in HF, sonicated, and purged with N

5：Sn is sputtered at 43 W for 20 min, followed by selenization at 450°C for 1 h in Ar. Film characterization includes XRD, SEM, AFM, thickness measurement, DRS, Raman, XPS. Devices are fabricated with Cr/Au electrodes. Photodetection is performed under 1064 nm laser, with I-V and I-t measurements. High-speed measurements use an optical chopper and oscilloscope. Data Analysis Methods:

Data analyzed using Cheung's method for diode parameters, power law for photocurrent dependence, exponential fitting for response times, and equations for sensitivity, responsivity, EQE, detectivity.