Demonstration of a Dual-Band InAs/GaSb Type-II Superlattice Infrared Detector Based on a Single Heterojunction Diode

We propose and demonstrate a new single heterojunction structure for dual-band detection based on type-II InAs/GaSb superlattices grown by metal-organic chemical vapor deposition. The structure simply consists of a p-type mid-wavelength contact layer, an n-type mid-wavelength absorber and an n-type long-wavelength absorber. At a small reverse bias, the presence of a potential barrier in the valence band between the two adjacent absorbers allows the mid-wavelength channel to work only; at a higher bias where the potential barrier no longer exists, photo-generated holes in the long-wavelength absorber are able to transport through the mid-wavelength absorber and reach the p-contact, making both channels to work. At −0.1 V and 77 K, the mid-wavelength channel exhibited a 50% cut-off wavelength of 3.5
$\mu \text{m}$
, a dark current density of
$2.4\times 10^{{-9}}$
A/cm
²
, and a peak specific detectivity of
$1.4\times 10^{{13}}$
cm
$\cdot $
Hz
^1/2
/W; while at −0.3 V the long-wavelength channel exhibited a 50% cut-off wavelength of 8.0
$\mu \text{m}$
, a dark current density of
$5.1\times 10^{-7}$
A/cm
²
, and a peak specific detectivity of
$3.6\times 10^{12}$
cm
$\cdot $
Hz
^1/2
/W.