Mid-IR Intraband Photodetectors with Colloidal Quantum Dots

Abstract

In this paper, we investigate an intraband mid-infrared photodetector based on HgSe colloidal quantum dots (CQDs). We study the size, absorption spectra, and carrier mobility of HgSe CQDs films. By regulating the time and temperature of the reaction during synthesis, we have achieved the regulation of CQDs size, and the number of electrons doped in conduction band. It is experimentally verified by the field effect transistor measurement that dark current is effectively reduced by a factor of 10 when the 1Se state is doped with two electrons compared with other doping densities. The HgSe CQDs film mobility is also measured as a function of temperature the HgSe CQDs thin film detector, which could be well fitted by Marcus Theory with a maximum of 0.046 ± 0.002 cm2/Vs at room temperature. Finally, we experimentally discuss the device performance such as photocurrent and responsivity. The responsivity reaches a maximum of 0.135 ± 0.012 A/W at liquid nitrogen temperature with a narrow band photocurrent spectrum.

Simulation and Design of HgSe Colloidal Quantum-Dot Microspectrometers

“…By controlling the reaction time and temperature, the energy gap of the CQDs becomes smaller, and as a result, the Fermi level is in the Se state, defined as the two electrons in the conduction band of each CQD being in the Se state and the Pe state being empty. Compared to other electron doping densities, the dark current of HgSe film is reduced [39,40]. On the other hand, the uneven distribution of quantum dot size will also have an impact on carrier mobility.…”

“…On the other hand, the uneven distribution of quantum dot size will also have an impact on carrier mobility. The carrier mobility of the HgSe film can be measured and calculated by the FET circuit, and the mechanism is explained by Marcus theory [40]: According to existing experimental conclusions, the influence of the size and size of the CQDs on the energy band can be further learned. The absorption peaks of HgSe redshift with increasing size, which is controlled by the reaction conditions for synthesizing CQDs [37,38].…”

“…On the other hand, the uneven distribution of quantum dot size will also have an impact on carrier mobility. The carrier mobility of the HgSe film can be measured and calculated by the FET circuit, and the mechanism is explained by Marcus theory [40]:…”

The Historical Development of Infrared Photodetection Based on Intraband Transitions

“…For example, CQDs are distinguished by an obvious quantum confinement effect, tunable size and bandgap, excellent photostability, and high integration [ 14 , 15 , 16 , 17 , 18 , 19 ]. The CQDs based on intraband transitions of absorption or emission can cover the entire infrared band and have spectral tunability [ 20 , 21 , 22 , 23 ], which have great advantages compared with other photoelectric materials. In Figure 1 , we mainly present QWIPs and quantum dots infrared photodetectors (QDIPs) based on intraband transition in recent years.…”

In Situ Mapping of the Vectorial Electric Field within a Nanocrystal-Based Focal Plane Array Using Photoemission Microscopy

“…HgTe nanocrystals (NCs) have emerged as a unique platform to address infrared wavelengths thanks to the gapless bulk HgTe and band engineering with quantum confinement. By tailoring the particle surface chemistry, NC arrays can be made conductive and photoconductive. − As a result, their use in advanced devices dedicated to infrared sensing and imaging appears as a viable alternative to epitaxially grown thin films. Compared with devices relying on epitaxially grown narrow-bandgap semiconductors, NCs lift the constraints on epitaxial growth, thereby facilitating the coupling to the readout circuit, including those with a few-micrometer pitch circuit .…”