An overview of the current status of the 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.

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We present simulation results on the current-voltage (I-V) characteristics of an InP-based AlAs/InGaAs resonant tunneling diode (RTD) with InAs subwell. Space-charge limited transport is accounted for using a self-consistent electrostatic potential calculated using the Hartree approximation. Three-dimensional scattering is simulated using the recently developed multiple sequential scattering theory. Interface roughness scattering is found to be dominant over polar phonon scattering in the devices studied. Of particular interest is interface-roughness (IR) scattering at the InGaAs/AlAs and InGaAs/InAs interfaces and its impact on the valley current. The existence of a critical terrace size that maximizes IR scattering is identified through simulation. The origin of the asymmetry commonly measured in the RTD I-V characteristic is discussed with respect to asymmetries in interface scattering. The use of the InAs subwell and associated interface roughness scattering to tune the peak current while keeping a nearly constant current peak-to-valley ratio is demonstrated.