Optimization of fabrication processes of the mesa-type GaAs:Te blocked-impurity-band detector
In this work, the device structure of the mesa-type GaAs:Te blocked-impurity-band detector was designed. The fabrication processes were presented briefly, and optimization of the fabrication processes was investigated. A 3-micron-thick SiO2 film was deposited as resist to substitute for photoresist in the 50-micron-deep mesa etching process. In addition, a bi-layer photoresist lithography technique was adopted to optimize the process of electrode fabrication. It is demonstrated that the device quality can be improved significantly after optimization.
Development for Germanium Blocked Impurity Band Far-Infrared Image Sensors with Fully-Depleted Silicon-On-Insulator CMOS Readout Integrated Circuit
We are developing far-infrared (FIR) imaging sensors for low-background and high-sensitivity applications such as infrared astronomy. Previous FIR monolithic imaging sensors, such as an extrinsic germanium photo-conductor (Ge PC) with a PMOS readout integrated circuit (ROIC) hybridized by indium pixel-to-pixel interconnection, had three difficulties: (1) short cut-off wavelength (120 $$\upmu $$μm), (2) large power consumption (10 $$\upmu $$μW/pixel), and (3) large mismatch in thermal expansion between the Ge PC and the Si ROIC. In order to overcome these difficulties, we developed (1) a blocked impurity band detector fabricated by a surface- activated bond technology, whose cut-off wavelength is longer than 160 $$\upmu $$μm, (2) a fully-depleted silicon-on-insulator CMOS ROIC which works below 4 K with 1 $$\upmu $$μW/pixel operating power, and (3) a new concept, Si-supported Ge detector, which shows tolerance to thermal cycling down to 3 K. With these new techniques, we are now developing a $$32 \times 32 $$32×32 FIR imaging sensor.
Antimony-doped silicon blocked impurity band (BIB) arrays for low flux applications
DRS is the inventor and a leading developer of Blocked Impurity Band detector technology for ground, airborne and space-based observing applications and the sole developer of antimony doped silicon (Si:Sb) blocked impurity band (BIB) FPAs. Arsenic doped silicon (Si:As) and Si:Sb arrays in 1282 pixel formats were developed by DRS for use on the Spitzer Space telescope. In the subsequent years these arrays were extended in both format and capability. 10242 pixel format, low flux Si:As arrays were developed for the NASA WISE mission, and Si:As and Si:Sb arrays were developed for higher flux applications such as JPL’s MegaMIR camera and Cornell’s FORCAST instrument for SOFIA, in both 2562 and 10242 pixel array formats. Si:Sb arrays have advanced to offer similar responsivity, response uniformity, high operability and low dark currents long associated with Si:As BIB arrays but with high quantum efficiency that extends to 40 μm, compared to only 28 μm for Si:As. Recently, Si:Sb detector material has been further developed for low flux astronomy applications. Specifically, Si:Sb material has been grown to satisfy exceptionally low dark current requirements (such as < 0.5 e-/s/pixel at 5 K) for large format focal plane arrays for future infrared telescopes. This paper will focus on the characterization of this low flux Si:Sb detector material