Comparative study of ultrafast intersubband electron scattering times at ̃1.55 μm wavelength in GaN/AlGaN heterostructures

We report on a comparative study of room temperature intersubband electron scattering lifetimes in GaN/AlGaN single and coupled double multiple quantum well (QW) samples with peak absorption wavelengths ranging from 1.4 to 1.7 μm. Using time-resolved pump-probe spectroscopy electron scattering times as short as ∼160 fs have been measured for a coupled QW sample and ≲300 fs for single QW samples. While no significant dependence on the excitation power has been observed, a decrease of the scattering times with increasing probe wavelength has been measured and may be attributed to monolayer fluctuations in the samples.

[1]  Claire F. Gmachl,et al.  Intersubband absorption in degenerately doped GaN/AlxGa1−xN coupled double quantum wells , 2001 .

[2]  J. Shah.  Ultrafast spectroscopy of semiconductors and semiconductor nanostructures , 1996 .

[3]  A. Cho,et al.  Growth and Characterization of GaN/AlGaN Superlattices for Near‐Infrared Intersubband Transitions , 2001 .

[4]  Norio Iizuka,et al.  Feasibility Study on Ultrafast Nonlinear Optical Properties of 1.55-µ m Intersubband Transition in AlGaN/GaN Quantum Wells , 1997 .

[5]  Arup Neogi,et al.  Intersubband transitions and ultrafast all-optical modulation using multiple InGaAs-AlAsSb-InP coupled double-quantum-well structures , 2001 .

[6]  Osamu Wada,et al.  Ultrafast intersubband relaxation (⩽150 fs) in AlGaN/GaN multiple quantum wells , 2000 .

[7]  Norio Iizuka,et al.  Electron Scattering Rates in AlGaN/GaN Quantum Wells for 1.55-µm Inter-Subband Transition , 1998 .

[8]  Ferreira,et al.  Evaluation of some scattering times for electrons in unbiased and biased single- and multiple-quantum-well structures. , 1989, Physical review. B, Condensed matter.

[9]  Susumu Noda,et al.  Carrier relaxation dynamics in an ultrafast all-optical modulator using an intersubband transition , 2001 .

[10]  Erich Gornik,et al.  High-power GaAs/AlGaAs quantum fountain unipolar laser emitting at 14.5 μm with 2.5% tunability , 1999 .

[11]  Claire F. Gmachl,et al.  Intersubband absorption at λ∼1.55 μm in well- and modulation-doped GaN/AlGaN multiple quantum wells with superlattice barriers , 2000 .