258 Gallium Nitride (GaN): Physics, Devices, and Technology
GaN/AlN QWs displaying ISB transitions in the near-IR can also be synthe-
sized by metalorganic vapor phase epitaxy (MOVPE) [51–53]. In this case, a criti-
cal parameter to attain devices in the telecommunication spectral range (1.3 µm,
1.55µm) is the reduction in growth temperature from the 1050°C–1100°C optimum
range for GaN growth down to 900°C–950°C (or even to 770°C [54]), to minimize
the GaN–AlN interdiffusion. Furthermore, deposition under compressive strain
(e.g., using AlN substrates) is recommended at these growth temperatures to prevent
the red shift of the ISB transition due to instabilities of the GaN/AlN interface [55].
Since GaN/AlN is a lattice-mismatched system (2.5 ...