
278 Gallium Nitride (GaN): Physics, Devices, and Technology
GaN/AlGaN QCDs operating in the near-IR have been reported [192,193], with
their structure illustrated in Figure 8.15. These devices take advantage of the polar-
ization-induced internal electric eld to design an efcient AlGaN/AlN (or GaN/
AlGaN) electron extractor where the energy levels are separated by approximately
the LO-phonon energy (~90 meV), forming a phonon ladder. The peak responsiv-
ity of these GaN/AlGaN QCDs at room temperature was ~10 mA/W [192,194].
Detectors containing 40 periods of active region with a size of 17 × 17 µm
2
exhibit
an RC-limited BW
–3 dB
cutoff frequency ...