Gas Source MBE Growth and Characterization of TlInGaAs/InP DH Structures for Temperature-independent Wavelength LD Application
Abstract : TlInGaAs/InP double-hetero (DH) structures were grown on (100) InP substrates by gas source MBE. The photoluminescence (PL) peak energy variation with temperature decreased with increasing Tl composition. For the DH with a Tl composition of 13%, the PL peak energy varied only slightly with temperature (-0.03 meV/K). This value corresponds to a wavelength variation of 0.04 nm/K and is much smaller than that of the lasing wavelength of InGaAsP/InP distributed feedback laser diodes (0.1 nm/K). TlInGaAs/InP light emitting diodes with 6% Tl composition were fabricated and the small temperature variation of the electroluminescence peak energy (-0.09 meV/K) was observed at the wavelength around 1.58 micrometers. The results are promising to realize the temperature-independent wavelength laser diodes, which are important in the wavelength division multiplexing (WDM) optical fiber communication systems.
Ultrafast carrier dynamics and saturable absorption in HgCdTe
The ultrafast carrier dynamics in Hg0.6Cd0.4Te and Hg0.33Cd0.67Te are studied using a femtosecond optical parametric oscillator and the optical transmission‐correlation spectroscopy method. The band gaps of these materials are 2.85 μm (0.435 eV) and 1.47 μm (0.844 eV) at room temperature, respectively. The collective relaxation occurs within the 0.5 to 2 ps range and a fast scattering process is observed in the 150 to 200 fs range. Saturation effects are detected in the 0.844 eV band gap sample resulting in a transmission maxima near 2 ps in addition to the standard transmission peak at zero time delay. The magnitude of the saturable absorption is also measured as a function of carrier density and initial kinetic energy of the photoexcited carriers.
InTlSb: An infrared detector material?
In1−xTlxSb is proposed as promising infrared material. A number of optical and structural properties are studied within local density‐functional theory. The alloy at x=0.09 is estimated to have a gap of 0.1 eV. Although TlSb is found to favor the CsCl structure, the zinc blende alloy is stable for low x values. A phase diagram is calculated to estimate the regions of stable phases and explore the conditions for growing narrow‐gap In1−xTlxSb alloys.