Uncooled Mid-wave Infrared Focal Plane Array Using Band Gap Engineered Mercury Cadmium Telluride Quantum Dot Coated Silicon ROIC

Abstract

The dominant photon detectors and focal plane arrays (FPAs) in the mid-wave infrared (MWIR) range (λ = 3 μm to 5 μm) use single crystal InSb and HgCdTe materials. The cost of these detectors is high, and cooling at approximately 80 K to 120 K is required to reduce the dark current. Colloidal quantum dots (CQDs) can be used to provide the speed and detectivity (D*) of the quantum detectors with lower fabrication costs than those of single crystal epitaxial materials. The aim of this study is to develop a MWIR area array sensor with an HgCdTe-ternary alloyed semiconductor CQD using a commercially available silicon readout integrated circuit (ROIC). First, we synthesized a solution processed HgCdTe CQD responsive in the MWIR range at room temperature and developed a Schottkey junction photodiode array of 10 × 10 pixels based on the same quantum dots (QDs) to produce a HgCdTe-Si interface suitable for a MWIR photodiode at room temperature. After ensuring its functionality, we developed a 320 × 256-pixel focal plane array (FPA) responsive in the MWIR region by hybridization of the HgCdTe CQD layer over a silicon ROIC die with a direct injection input circuit. The FPA was operated using an indigenously developed Field Programmable Gate Array (FPGA)-based drive unit, and different IR targets were imaged to evaluate its use as a low-cost MWIR FPA. NEΔT value of 4 K achieved at room temperature.

The Strong Confinement Regime in HgTe Two-Dimensional Nanoplatelets

“…Over the past decade, infrared optoelectronics 2 have also generated interest with applications such as solar cells 3,4 and low-cost infrared (IR) sensors 5,6,7,8,9 including focal plane arrays. 10,11,12 For these IR applications, narrow band gap materials such as lead and mercury chalcogenides are used, and the relative change of the band gap resulting from confinement can be even more important. Thus, the lowest energy optical feature of HgTe can be tuned from the THz 13,14 to the visible range (i.e.…”

“…In such an application, the confinement-induced renormalization of the band gap corresponds to a few tens of percent. Over the past decade, infrared optoelectronics has also generated interest with applications such as solar cells , and low-cost infrared (IR) sensors − including focal plane arrays. − For these IR applications, narrow band gap materials, such as lead and mercury chalcogenides, are used, and the relative change of the band gap resulting from confinement is even more important. Thus, the lowest-energy optical feature of HgTe can be tuned from the THz , to the visible range (i.e., over two orders of magnitude of energy) only using confinement, due to the lack of bulk band gap.…”

Correlating Structure and Detection Properties in HgTe Nanocrystal Films

“…Among them, HgTe is certainly offering the widest spectral tunability and the most impressive device performance for infrared light emission [1][2][3] and detection. [4][5][6] Over the recent years, the integration of HgTe CQDs as absorbing layers in IR sensors has been developed from the basic demonstration of IR photoconduction, 7,8 to highly complex devices including focal plane arrays [9][10][11][12][13] and unconventional detectors with enhanced light-matter coupling to increase their light absorption. [14][15][16][17][18] A significant part of the efforts has been dedicated to improve the device, including the development of vertical geometry devices (i.e.…”

“…The II–VI semiconductors are the most mature materials in the colloidal quantum dot (CQD) form and have been extensively used for optoelectronic applications. Among them, HgTe certainly offers the widest spectral tunability and the most impressive device performance for infrared light emission − and detection. − Over recent years, the integration of HgTe CQDs as absorbing layer in IR sensors has been developed from the basic demonstration of IR photoconduction , to highly complex devices including focal plane arrays − and unconventional detectors with enhanced light-matter coupling to increase their light absorption. − A significant part of the efforts has been dedicated to improve the device, including the development of vertical geometry devices (i.e., photodiodes) thanks to the development of hole extracting layers and unipolar barriers , suitable for narrow band gap materials. In addition, planar geometry devices (i.e., phototransistors) ,, enable to efficiently control the carrier density by applying a gate bias, which maximizes the signal-to-noise ratio.…”

Large Photogain in Multicolor Nanocrystal Photodetector Arrays Enabling Room-Temperature Detection of Targets Above 100 °C

“…Furthermore, it has been shown that solution patterned, planar devices are also capable of imaging, given an increased number of pixels. Indeed, since submitting this work initially, several important focal plane detector arrays have been reported using similar design principles. − …”