Detectivity Enhancement in Cascade Infrared Upconverter Utilizing AlInP Hole-Blocking Layer

A cascade infrared upconverter (CIUP) avoids mechanical bonding between photodetectors and read-out integrated circuits, being a promising candidate for very large-format infrared imaging. This letter demonstrates a CIUP with an Al
_0.52
In
_0.48
P hole-blocking layer whose valence band discontinuity with GaAs is large, which will tightly confine injected holes into the emission region. The device shows a peak response wavelength at
$4.9~\mu \text{m}$
and a peak emission wavelength at 870 nm. At 1.4 V bias and 78 K, shot noise limited detectivity of the upconversion system is
$1.17\times 10^{9}$
Jones, about one order of magnitude higher than the previously reported CIUP with an AlAs hole-blocking layer.