摘要:

We have calculated the binding energy of hydrogenic impurity states in a GaAs–GaAlAs heterojunction in which the electrons are confined in a triangular potential well formed by charge transfer from the GaAlAs side of the heterojunction to the GaAs side. The binding energy of the impurity is calculated as a function of the position of the impurity in the quantum well and as a function of the electric field which arises in the heterojunction because of the charge transfer. A variational method was used and screening effects were neglected. We find that the peak value of the binding energy of the hydrogenic impurity as a function of distance of the impurity from the boundary of the heterojunction increases with electric field and has a value in strong electric fields which exceeds that predicted for the confinement of hydrogenic impurities in a strictly two‐dimensional quantum well. With increasing electric field, the location of that peak is found to move toward the heterojunction.

ISSN:0734-211X    

DOI:10.1116/1.583017

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Deep level characterization of Si‐doped AlGaAs layers and the interface of selectively doped N‐AlGaAs/GaAs heterojunctions grown by MBE is reported. Three electron traps have been detected by DLTS in AlGaAs layers and in N‐AlGaAs/GaAs heterostructures. Two of them are the main dominant levels in the bulk of Si‐doped AlGaAs, which are identified as the well known DX centers. The remaining one shows a peak in concentration near the AlGaAs side of the heterojunction interface in the N‐AlGaAs/GaAs structure and is identified as one of the DX related levels. The effect of these levels on the mobility of electron gas at the N‐AlGaAs/GaAs heterojunction is investigated.

ISSN:0734-211X    

DOI:10.1116/1.583018

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

We have studied Ga0.47In0.53Al/Al0.48In0.52As quantum wells grown by molecular beam epitaxy (MBE). The smoothing effect of a Ga0.47In0.53As buffer layer results in narrow linewidth. Strained layer superlattices of Ga0.85In0.15As/GaAs exhibit excitonic transition at 77 and 300 K as seen by absorption measurement. A model is proposed to explain the different energy transitions.

ISSN:0734-211X    

DOI:10.1116/1.583019

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A process for fabricating sub‐half‐micrometer‐length gates for GaAs MESFETs is described. This process, which uses conventional photolithography, incorporates a number of special techniques to produce the gates from a photomask having 1‐μm‐length gate patterns. Gates produced by this process have shapes and cross‐sectional areas that are comparable to those of gates produced by liftoff using sub‐half‐micrometer electron‐beam lithography. Gates with lengths less than 0.2 μm have been fabricated.

ISSN:0734-211X    

DOI:10.1116/1.583021

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

We report on a technique developed for improving quantitative analysis of Auger electron spectroscopy data by monitoring line shapes, peak energies, and ratios, in addition to peak heights, as a function of sputtering time. The technique proves to be useful for analysis of InSb‐native oxide interfaces due to the sensitivity of the AES lines of the different constituents to their chemical state. Thus important information can be obtained on the detailed structure and composition of these oxides and their interfaces, specifically, concerning quantitative determination of interface boundaries. The technique is discussed with typical results and possible extension to other interfaces.

ISSN:0734-211X    

DOI:10.1116/1.583022

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

We demonstrate the use of a nude ion gauge flux monitor coupled to a high resolution digital voltmeter in setting the beam fluxes for the growth of In0.53Ga0.47As on InP by molecular beam epitaxy (MBE). Computer control has been implemented for both the flux setting and growth operations. Typical lattice mismatches were less than 1.5×10−3. We have also demonstrated, to the best of our knowledge, the first totally automated growth of In0.53Ga0.47As on InP by MBE. This growth incorporated computerized flux settings, oxide removal, and growth and gave a lattice mismatch of 1.0×10−3.

ISSN:0734-211X    

DOI:10.1116/1.583023

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Epitaxial Ge and Si films have been grown by primary ion deposition from laser‐induced plasmas. The plasmas were formed by focusing 15 ns, 107–108W cm−2, pulses of 5 eV photons from a KrF excimer laser onto Ge or Si single crystal wafer targets. Time‐of‐flight, current‐voltage, and film‐thickness distribution measurements established that neutral atoms and ions were emitted from Ge targets with mean velocities of 1.0–1.6×106cm s−1(corresponding to average kinetic energies of 40 to 100 eV) in a distribution that was strongly peaked in the direction normal to the target surface. Macroscopic (∼1 μm diam) particles were also emitted. A shutter, synchronously triggered with the laser pulses through a delay circuit, was used as a velocity filter for removing from the beam particles with velocities up to 1.2×104cm s−1. Epitaxial Ge films were grown on semi‐insulating (100) GaAs substrates at temperatures between 300 and 450 °C and epitaxial Si was grown on (100) Si at 700 °C. Deposition rates were typically 0.5–1 μm h−1. Hall effect measurements carried out on the Ge/GeAs heterostructures showed that the Ge films, ∼1 μm thick, wereptype with room temperature carrier concentrations of ∼1×1018cm−3and hole mobilities of ∼150 cm2/V s.

ISSN:0734-211X    

DOI:10.1116/1.583024

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A high output production silicon molecular beam epitaxy apparatus for 4‐in.‐diam wafers is described. Throughput time in an ordinary operation is as short as 20 min/wafer with the help of cassette loading and high growth rates around 20 Å/s. Silicon is deposited from a sweep eb‐gun with a hearth capacity of 50 cm3. Rotation of the wafer yields a thickness uniformity of<±5% across a 4‐in. wafer. Antimony as a dopant is evaporated from a conventional Knudsen cell and doping uniformity of<±10% is obtained. The uniformity variation reflects temperature variations of ±5 °C across a typical wafer. Good heating uniformity is achieved with a graphite meander heater. Low temperature cleaning of the substrate surface is also described.

ISSN:0734-211X    

DOI:10.1116/1.583025

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Chemical oxidation of InP (100) was carried out in hot nitric acid. Composition of the oxides was determined by means of Auger electron spectroscopy employing layer by layer etching with Ar+ions. It is shown that the composition of the chemical oxide is similar to that of anodic oxides. They are characterized by substantial compositional nonuniformity, that increases with increase of oxide thickness and decreases with annealing temperature. Annealing atT=280–400 °C results in improved compositional uniformity and a higher concentration of oxidized phosphorus in the oxide. Annealing at such temperatures, especially atT≥400 °C, is accompanied by broadening of the interface between the oxide and InP and a substantial concentration of unoxidized phosphorus near the interface. The interfacial broadening and concentration of unoxidized phosphorus are considered to be the result of reaction between P‐oxide and InP.

ISSN:0734-211X    

DOI:10.1116/1.583026

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A new TiSi2self‐alignment formation in the source/drain region and gate electrode, which realizes a high performance metal–oxide–silicon field effect transistor (MOSFET) with a low‐resistance interconnect, is described. The self‐alignment formation utilizes Ti‐silicide deposition and its subsequent oxidation, leading to a TiSi2/poly‐Si gate isolated from the TiSi2/n+‐ andp+‐diffusion source/drain inp‐well CMOS devices. A sheet resistance of about 1.5 Ω/sq on TiSi2/n+‐ andp+‐diffusion and 4 Ω/sq on the TiSi2/poly‐Si gate have been achieved. Contact resistance between the TiSi2layer and Al wire was also 0.08 μΩ cm2. MOSFET characteristics with the TiSi2layer are for the most part similar to those of poly‐Si gates.

ISSN:0734-211X    

DOI:10.1116/1.583028

出版商:American Vacuum Society    

年代:1985

数据来源: AIP