摘要:

Si/SiO2etch properties have been studied in CF4and CHF3cylindrical magnetron rf discharges as a function of magnetic field strength. As the magnetic field strength increases from 0 to 250 G, radical densities continuously increase and dc bias voltages exponentially decrease. The maximum etch rates of Si and SiO2, however, occur at an intermediate value of magnetic field strength which corresponds to the self‐bias voltage being between 25 and 50 V. Using magnetic field strengths near the maximum etch rate, we obtained vertical features having <2000 A˚ widths and trenches deeper than 2 &mgr;m. Etch rates exceeding 2500 A˚/min were obtained in a CF4plasma, with little or no radiation damage, and with minimum contamination of the surface.

ISSN:0003-6951    

DOI:10.1063/1.103322

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The formation of high‐resistivity (>107&OHgr;/&laplac;) regions in GaAs‐AlGaAs heterojunction bipolar transistor (HBT) structures by oxygen and hydrogen ion implantation has been investigated as a function of ion dose and subsequent annealing temperature (400–700 °C). Isolation leakage currents as low as 8 &mgr;A mm−1at 6 V can be achieved between 100‐&mgr;m‐wide ohmic contacts separated by a 16 &mgr;m spacing. The isolation of these 1.8‐&mgr;m‐thick heterojunctions requires up to six different energy oxygen implants (40–400 keV) and three different energy proton implants (100–200 keV) with doses in the mid 1012cm−2range for O+and 5×1014cm−2for H+ions. Similar results can be achieved by substituting a MeV energy oxygen implant for the proton implants. The optimum post‐implant annealing temperature depends on the ion dose but is in the range 500–600 °C. The evolution of the sheet resistance of the implanted GaAs‐AlGaAs material with annealing is consistent with a reduction in tunneling probabilities of trapped carriers between deep level states for temperatures up to ∼600 °C, followed by significant annealing of these deep levels. Small geometry (2×9 &mgr;m2) HBTs exhibiting current gain of 44 and cutoff frequencyfTas high as 45 GHz are demonstrated using implant isolation.

ISSN:0003-6951    

DOI:10.1063/1.102683

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the growth of InGaAs and InGaAsP quantum well heterostructures on InP substrates with [011¯] oriented grooves. We have shown that growth of these materials on non‐planar substrates can result in lattice‐mismatched layers on orientations other than (100) which in some cases gives rise to dislocations. In addition, the lateral patterning of quantum wells and quantum wire‐like structures has been demonstrated in this material system. Finally, a quantum well laser, wherein lateral patterning of the well thickness was achieved by growing in a flat‐bottomed groove, was fabricated. Without any additional growth steps these lasers exhibit a single stable spatial mode due to the waveguide formed at the groove.

ISSN:0003-6951    

DOI:10.1063/1.102665

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The density of etch pits and the concentration of O in melt‐grown CdTe increased as the residual gas pressure in ampoules during preparation increased. The etch pit density increased proportionally to the integral strength of an infrared TeO2absorption band, which presents the oxygen concentration.

ISSN:0003-6951    

DOI:10.1063/1.102666

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Microcrystalline Sm‐Fe‐V magnets with a ThMn12crystal structure were prepared by mechanical alloying and a subsequent reaction heat treatment. In Sm15Fe70V15a coercivity of 11.7 kOe is obtained. This is the best value reported so far for 1:12 magnets. As expected from their high anisotropy fields, the 1:12 magnets, therefore, show coercivities which are common in the Nd‐Fe‐B system.

ISSN:0003-6951    

DOI:10.1063/1.102662

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A high band‐gap material surrounded by two short‐period superlattices of lower band gap is proposed for carrier confinement to the barrier. The combined structure behaves as a Fabry–Perot cavity for carriers as long as coherence of the carrier wave function is maintained. Since Bragg confinement and creation of a mini‐gap energy state is sensitive to the value of the carrier effective mass, the system is also an effective mass filter for light holes.

ISSN:0003-6951    

DOI:10.1063/1.102663

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.102664

出版商:AIP    

年代:1990

数据来源: AIP