Volume 90, Issue 8, 15 October 2001
Index of content:
Extraordinarily wide optical gain spectrum in 2.2–2.5 μm In(Al)GaAsSb/GaSb quantum-well ridge-waveguide lasers90(2001); http://dx.doi.org/10.1063/1.1391421View Description Hide Description
A wide optical gain spectrum with full width at half maximum Δλ≈350 nm has been demonstrated in midinfrared (2.2–2.5 μm) room-temperature-operated InGa(As)Sb/GaSb quantum-well (QW) ridge-waveguide diode lasers. A QW width of 200 Å ensured a small energy separation between the first and second quantized states in the QW. Transitions from both quantized states contributed equally to the overall gain spectrum when the optical loss was optimized.
90(2001); http://dx.doi.org/10.1063/1.1401796View Description Hide Description
We have observed electron and hole trapping phenomena in thin films of obtained by plasma assisted deposition. Limited thickness dependent measurements suggest that the holes are trapped uniformly through the film while the electrons trap at the interface. Relaxation of the trapped holes occurs rapidly after removal of negative stress (∼90% in 15 min), while electron relaxation postpositive stress occurs more slowly (∼10% in 100 min). Cycling between states of positive trapped charge and negative trapped charge by application of the appropriate stressing voltage was observed.
90(2001); http://dx.doi.org/10.1063/1.1403668View Description Hide Description
We report the growth of a transparent, -type semiconductor, CuSCN, in nanometer sized channels of a thin polyester foil. High energy heavy ion irradiation and subsequent etching is used to prepare vertical cylindrical channels in polymers with diameters in the range 30–3000 nm. Electrodeposition is then used to fill these channels with polycrystalline CuSCN. The embedding is robust against mechanical stress on the foil. Since the bulk modulus of the inorganic CuSCN is larger than that of the polymeric matrix, only small forces act on the embedded semiconductor, resulting in low electrical changes upon bending or flexing of the foil. Dissolving the polyester matrix results in free-standing semiconductor columns with height-to-diameter ratios in excess of 100.
90(2001); http://dx.doi.org/10.1063/1.1403667View Description Hide Description
The Ge/Si interdiffusion in GeSi dots grown on Si (001) substrate by gas-source molecular beam epitaxy is investigated. Transmission electron microscopyimages show that, after annealing, the aspect ratio of the height to base diameter increases. Raman spectra show that the Si–Ge mode redshifts and the intensity of the local Si–Si mode increases with the increase of annealing temperature, which suggests the Ge/Si interdiffusion during annealing. The photoluminescence peaks from the dots and the wetting layers show blueshift due to the atomic intermixing during annealing. The interdiffusion thermal activation energies of GeSi dots and the wetting layers are 2.16 and 2.28 eV, respectively. The interdiffusion coefficient of the dots is about 40 times higher than that of wetting layers and the reasons were discussed.
90(2001); http://dx.doi.org/10.1063/1.1402664View Description Hide Description
The diffusion of boron (B) in germanium(Ge) is studied. B was introduced in Ge wafers by ion implantation, and concentration profiles after furnaceannealing were obtained using secondary ion mass spectroscopy. The diffusion coefficient and solid solubility of B in Ge has been calculated to be and respectively, at 850 °C by fitting experimentally obtained profiles. This value of diffusion coefficient is at least two orders of magnitude lower than the minimum value reported in the literature for B diffusion in Ge. The results are significant as they question the general agreement about vacancydiffusion as the mechanism responsible for diffusion of B in Ge.