The electrochemical capacitance-voltage (ECV) technique was used to measure the carrier concentration profiles in St. Using the conventional parallel-equivalent circuit model of the Schottky junction to describe the electrolyte-silicon barrier we found excellent agreement between ECV and four-point probe analyses within +_10 to 20% for bulk Si uniformly doped p-and n-type from 1012 to 1018 cm -~. In this concentration range accuracy limits are determined mainly by the precise measurement of the area of the electrolyte-St contact. For the anodic etching of St, a constant effective dissolution valence of z = 3.7 was used throughout the measurements. Investigations with isotype and anisotype doping transitions were performed employing ECV and other profiling techniques for comparison.

No abstract

A two-step wet chemical etching process using HBr and HBr:K2Cr2O7 was developed in order to fabricate high-quality V-grooves in InP (100) wafers. A 40 nm titanium film, which was patterned by conventional photolithography and liftoff, was used as the etching mask. The {111}A sidewalls are mirrorlike with an arithmetic average roughness of less than 0.4 nm. The tip radius of the V-grooves is approximately 7 nm. Both values were determined by atomic force microscopy. InfrocluctionEver since they were first suggested, low-dimensional structures have generated wide interest. Due to their reduced dimensionality, the electronic density of states is increasingly confined from the common square-root dependence in bulk semiconductors through a steplike function for two-dimensional quantum wells (QWs) and sawtooth-like singularities for one-dimensional quantum wires (QWRs) to S functions for zero-dimensional quantum dots (QD5).' From the device point of view, the steady constriction of the density of states has several beneficial results, since basically the distribution of electrons and holes over a wide energy range is eliminated, thus leading to improved device characteristics. For lasers with quantum structures as the active region, the threshold current density becomes smaller' and less temperature-sensitive2 with decreasing dimensionality. Simultaneously, the optical gain increases dramatically.' Due to the modified density of states, the linewidth-enhancement factor is expected to be extremely small,3 which leads to improved noise behav-ior3'4 and increased relaxation oscillation frequency.3A QW laser can be easily grown on planar substrates by controlling the growth time. The main impediment of realizing QWR and QD lasers is the very size of the quantum structures in two or three dimensions lying in the range of de Broglie's wavelength.GaAs/AlGaAs QWR lasers have been fabricated using anisotropic growth in V-grooves.5 Conventional lithography in combination with wet chemical etching was used to fabricate the V-grooves. The lateral current confinement was realized by H-implanted areas which must be aligned with a precision of less than 1 p.m. Such accurate alignment is unnecessary if a set of QWRs is used in parallel.6 Lasers with strained self-organized QD5 grown in the Stranski-Krastanov mode were demonstrated.7 The

No abstract