Influence of back-to-back junctions on the formation of photoelectric characteristics of MIS structures

The paper presents the results of a comprehensive study on a dual-barrier silicon photodiode structure, Au–SiO 2 ·nSi–Au, featuring back-to-back rectifying metal-semiconductor junctions operating in both photodiode and photovoltaic modes. The peak spectral photosensitivity is observed at λ ≈ 0.85 – 0.90 µm, and the incorporation of the SiO 2 layer broadens the spectral response by 20 – 30 % via barrier and tunneling carrier transport mechanisms. The short-circuit photocurrent (I sc ) increases from 0.30 to 0.50 µA at low illumination levels and saturates at 0.65 – 0.67 µA for Φ ≥ 400 – 500 lx; the open-circuit voltage is V oc = 0.065 – 0.067 V. At an applied voltage of 6 V, the photocurrent reaches approximately 20 µA, while in the range of 0.02 – 0.10 V, the ideality factor is n = 1.7, indicating the contribution of generation-recombination processes and tunneling. The transient response is characterized by a rise time of t r = 88.7 ns, a fall time of t f = 109.2 ns, a carrier lifetime of τ = 56.3 ns, and an overall response time of t resp ≈ 10 −7 s. Under reverse bias from 0 to 6 V, the space charge region (SCR) width increases from 0.72 to 1.95 µm, and the maximum electric field strength rises from 2.2·10 4 to 6.0·10 4 V/cm. The aggregate of the obtained parameters demonstrates that the proposed structure is promising for high-speed near-infrared (NIR) photodetector applications.

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