NIIS Electronics

HAWAII-2 Array Specifics

NIIS uses the Hawaii-2 PACE 2048x2048 IR array from Teledyne Scientific and Imaging, LLC, a Teledyne Techonologies Incorporated company (formally Rockwell Scientific). This Hawaii-2 array has 18µm pixels with well depths of 100,000 e- and is comprised of four fully independent 1024x1024 quadrants with outputs configured as either 1 per quad or 8 per quad. Each quadrant contains a vertical and horizontal digital shift register for addressing the pixels in the array. The horizontal register requires five clocks where as the vertical register requires only two clocks. To obtain video output, the horizontal register is clocked in the fast direction with the vertical register being clocked in the slow direction. The four quadrants are electrically independent except for the multiplexer substrate and detector substrate connections. Each of the multiplexer quadrants are oriented with the fast (horizontal) and slow(vertial) readout diections as shown in the image below:

The PACE verision of the Hawaii-2 array uses Liquid Phase Epitaxy (LPE) to deposit detector HgCdTe on sapphire, 2.5µm. According to the Gemini NIFS group, the PACE substrate advantages and dissadvantages are as follows. Advantages include that this substrate is tried and proven, is lower risk, lower cost and more redily available. Disadvantages include a high dark current which limits obserations, low Quantum Efficiency which varies with temperature, especially temperatures below 70K, and there are persistence problems such as bright OH airglow leaving remnants when switching between gratings and bright standard and reference stars leaving remnants. The image below is a cross-sectional view of the Hybrid assembly of a HgCdTe detector. More specifics on the detector can be found in the table below.


HAWAII-2 specification table:
The specifications apply to array mean values.
Parameter Specification Goal
Format 2048x2048 2048x2048
Pixel Pitch μm 18 18
Fill Factor 90 90
Quantum Efficiency(77K)@2.3μm 55% 75%
Long wavelength cutoff μm 2.5 2.5
Short wavelength cut on μm 0.9 0.9
Read noise: multiple sample(e-@77K) ‹15 ‹5
Dark Current (e-/s @ 77K, Vb=0.5V) ‹1 ‹0.1
Well Capacity (e-, Vb=0.5V) 60,000 100,000
Yield (working pixels) ›95% ›99%
Temperature 77K 77K