Resonant interband tunneling diodes on silicon substrates are demonstrated using a Si/Si 0.5 Ge 0.5 /Si heterostructure grown by low temperature molecular beam epitaxy which utilized both a central intrinsic spacer and ␦-doped injectors. A low substrate temperature of 370°C was used during growth to ensure a high level of dopant incorporation. A B ␦-doping spike lowered the barrier for holes to populate the quantum well at the valence band discontinuity, and an Sb ␦-doping reduces the doping requirement of the n-type bulk Si by producing a deep n ϩ well. Samples studied from the as-grown wafers showed no evidence of negative differential resistance ͑NDR͒. The effect of postgrowth rapid thermal annealing temperature was studied on tunnel diode properties. Samples which underwent heat treatment at 700 and 800°C for 1 min, in contrast, exhibited NDR behavior. The peak-to-valley current ratio ͑PVCR͒ and peak current density of the tunnel diodes were found to depend strongly on ␦-doping placement and on the annealing conditions. PVCRs ranging up to 1.54 were measured at a peak current density of 3.2 kA/cm 2 .

The effects of interface roughness scattering in a resonant-tunneling diode are examined with the selfconsistent Born and the multiple sequential scattering algorithm for various interface roughness correlation lengths. The effect of a self-consistent treatment of the scattering self-energies with the quantum charge and the electrostatic and exchange-correlation potentials is demonstrated. The effects of the scattering assisted charge and the exchange and correlation potential on the spurious bistability obtained in simulations of a symmetric resonant-tunneling diode is shown. ͓S0163-1829͑98͒05932-3͔

Photoluminescence (PL) studies of bulk and epitaxial CdTe samples obtained from several sources are discussed. Steady state PL measurements were carried out at temperatures ranging from 16–300 K. The effects of surface preparation, substrate temperature, and film thickness were studied in detail for homoepitaxial films grown on the (111)A and (100) planes of CdTe. PL studies of epitaxial CdTe films grown on (0001) sapphire by molecular beam epitaxy (MBE), by hot wall MBE, and by metal-organic chemical vapor deposition (MOCVD), and on the (111)B and (100) planes of GaAs by MBE have also been completed. The CdTe epilayers on sapphire and GaAs substrates typically display a bright PL spectrum dominated by the near edge peak at 1.58 eV (77 K). In addition, a number of films exhibit a near edge peak at 1.503 eV at 300 K, which is indicative of high quality epitaxy and which allowed direct measurement of the room temperature band gap of CdTe. PL studies of epitaxial Cd1−x MnxTe films grown by MBE on 5.0 μm thick CdTe buffer layers on GaAs substrates reveal shifts of the band gap into the visible spectral region with increasing x accompanied by a significant increase in edge peak magnitude.

The contributions of interface roughness scattering and polar optical phonon scattering to the valley current of In 0.53 Ga 0.47 As/AlAs/InAs resonant tunnelling diodes (RTDs) are theoretically found to be comparable. An In 0.53 Ga 0.47 As/AlAs/InAs RTD design is suggested to experimentally observe the phonon peak which has never been observed in this material system. Such a device will provide a calibration point for the theoretical calculations.

No abstract