Abstract
Searching for innovative approaches to detect single photons remains at the center of science and technology for decades. This paper proposes a zero transit-time, non-avalanche quantum capacitive photodetector to register single photons. In this detector, the absorption of a single photon changes the wave function of a single electron trapped in a quantum dot (QD), leading to a charge density redistribution nearby. This redistribution translates into a voltage signal through capacitive coupling between the QD and the measurement probe. Using InAs QD/AlAs barrier as a model system, the simulation shows that the output signal reaches ~4 mV per absorbed photon, promising for high-sensitivity, ps single-photon detection.
Highlights
Photodetectors are indispensable components in most optoelectronic systems [1,2,3,4]
We proposed a novel quantum capacitive photodetector for registering single photons. The operation of this detector relies on the charge redistribution in the quantum dot (QD) upon single photon absorption
We implemented the concept in an InAs/AlAs model system by COMSOL simulation, which showed that an output voltage signal of the order of ~4 mV could be created by the detector in response to single photon absorption
Summary
Photodetectors are indispensable components in most optoelectronic systems [1,2,3,4]. Si quanta image sensors (QIS) achieved room-temperature, non-avalanche single photon detection by transferring the photoelectron to an ultralow capacitance (C~400 aF) floating diffusion region such that a photovoltage conversion gain of ΔV = e-/C~0.4 mV was achieved per photoelectron [22,23] This conversion gain is well above the noise level of ~0.1 mV in 65 nm complementary metal-oxide-semiconductor technology (CMOS) node and enables high-sensitivity single photon detection. Similar to the scenario in single electron transistors (SETs) [29], the output voltage is proportional to 1/C, where C is a small effective capacitance (~1100 aF) between the QD and the probe We term this detector a quantum capacitive photodetector (QCP) because the charge density redistribution due to the change in the wave function upon optical excitation is a quantum mechanical phenomenon rather than a classical one. Our results show that the proposed QCP that harnesses the quantum nature of electrons may open a new avenue for single-photon detections
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