Two different approaches, a photoconductive response technique and a correlation of lasing thresholds with theoretical threshold carrier concentrations have been used to determine Auger lifetimes in InAs/GaInSb quantum wells. For energy gaps corresponding to 3.1–4.8 μm, the room-temperature Auger coefficients for seven different samples are found to be nearly an order-of-magnitude lower than typical type-I results for the same wavelength. The data imply that at this temperature, the Auger rate is relatively insensitive to details of the band structure.

We have observed a large increase in the magnetoresistance (MR) of molecular beam epitaxy grown Bi thin films, which were subjected to a postannealing procedure 3 °C below the Bi melting point. We have achieved an increase in the MR by a factor of 2560 at helium temperatures compared with of 343 for an as-grown film. The enhancement of the MR in the annealed films is due to higher electron and hole mobilities (μe≈1×106 cm2/V s at 5 K) relative to those of the as-grown films (μe≈9×104 cm2/V s at 5 K). The enhancement of the mobility in the annealed films is also supported by the observation of Shubnikov–de Haas oscillations.

A 25-stage interband cascade laser with a W active region and a third hole quantum well for the suppression of leakage current has exhibited lasing in pulsed mode up to 286 K. A peak output power of 160 mW/facet and a slope efficiency of 197 mW/A per facet (1.1 photons per injected electron) were measured at 196 K. Above 200 K, the characteristic temperature was higher (T0=53 K) and the threshold current densities lower than for a previously reported W interband cascade laser without the third hole quantum well.

Optically pumped type-II W lasers emitting in the mid-infrared exhibited continuous-wave (cw) operating temperatures of 290 K at λ=3.0 μm and 210 K at λ=6.1 μm. Maximum cw output powers for 78 K were 260 mW at λ=3.1 μm and nearly 50 mW at λ=5.4 μm. These high maximum temperatures were achieved through the use of a diamond-pressure-bonding technique for heat sinking the semiconductor lasers. The thermal bond, which is accomplished through pressure alone, permits topside optical pumping through the diamond at wavelengths that would be absorbed by the substrate.

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