Noise Characteristics of MgZnO-Based Metal–Semiconductor–Metal Photodetector

The noise characteristics of wurtzite MgZnO metal-semiconductor-metal photodetectors (PDs) are investigated by a proposed equivalent noise circuit model considering the effects of thermal noise and shot noise induced by the resistances and fluctuations of photogenerated carriers, respectively. Then, the impact of series and enhanced gain peaking techniques on the noise properties of the PDs is studied in detail. To verify the accuracy and effectiveness of this model, the computed noise power spectral density results are compared with the simulated data from Multisim. Results show that the output noise power is mainly determined by thermal noise when the PD works in a high-frequency region. These two gain peaking techniques, specifically, the enhanced gain peaking can decrease the shot noise power and the thermal noise power due to the leakage resistance by approximately 40 dBm/Hz, respectively, because of the introduction of gain peaking inductance and capacitance. At an applied bias of 1 V, the achieved noise equivalent power and the corresponding normalized detectivity of the thermal noise due to the parasitic resistance of the enhanced gain peaked circuit are approximately 1.28 x 10 ^-7 W and 1.64 x 10 ¹² Jones, respectively, with an incident light wavelength of 266 nm. This paper is valuable for developing high-speed MgZnO PDs.