摘要:

We have investigated different metal contacts (Cr/Au, Ti/Pt/Au, and Au) onp‐type GaSb, grown by the molecular beam epitaxy. For Au contacts, specific contact resistivities in the range of 1.4×10−8–7.8×10−8Ω cm2have been obtained. These are the lowest values ever reported forp‐type GaSb. A simple procedure for surface preparation is also reported.

ISSN:0734-211X    

DOI:10.1116/1.587979

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The sequential tunneling of electrons throughn‐type GaAs/AlGaAs multiple‐quantum‐well (MQW) structures with Schottky and ohmic contacts is reported. Two series of tunnelings corresponding to those between the ground state and the first and second excited states were observed in low‐temperature current–voltage (I–V) characteristics in 200‐Å‐period and 240‐Å‐period MQWs. The oscillations in the conductance (G) and steplike features in theI–Vcharacteristics were found to be persistent up to 200 K. Unlike previous investigations using structures with nominally undoped MQW regions, S‐shaped steplike features in theI–Vcharacteristics corresponding to the negative differential resistance (NDR) effect, were observed at low temperature in our MQW structures with Schottky contacts and uniformly dopedn‐type MQW regions. The electron tunneling process through the MQW structures is discussed in terms of the creation and propagation of high electric field domains as a function of the applied bias.

ISSN:0734-211X    

DOI:10.1116/1.587984

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Stable passivation of GaAs surfaces and AlGaAs/GaAs heterojunction bipolar transistors has been achieved using sulfide solutions and SiNxoverlayers. The SiNxlayers are deposited at ∼200 °C using electron cyclotron resonance plasma‐enhanced chemical vapor deposition technique. The capacitance–voltage measurements indicate a substantial reduction in the density of electronic defects at the SiNx/S–GaAs interface as a result of annealing in N2ambient. The base current of a 36×36 μm2AlGaAs/GaAs heterojunction bipolar transistor is reduced by approximately two orders of magnitude in the low collector current regime by using sulfide treatment, SiNxdeposition, and anneal. Both the Al/SiNx/S–GaAs capacitors and transistors are stable for several months with no noticeable degradation in their electrical characteristics.

ISSN:0734-211X    

DOI:10.1116/1.588001

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The use of multiple energy He+implantation for producing electrical isolation between neighboring GaAs/AlGaAs or GaAs/InGaP heterojunction bipolar transistors is found to alleviate the problem of time‐dependent current gain behavior found in H+isolated devices. This latter phenomenon is ascribed to rapid diffusion of atomic hydrogen into the active base region during the anneal required to maximize the resistance of the implanted areas, and the subsequent reactivation of passivated C acceptors in the base. Replacement of H+with He+ions in the implant scheme produces similar high resistance isolation regions (≳108Ω/cm) without the presence of hydrogen passivation effects.

ISSN:0734-211X    

DOI:10.1116/1.587975

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Small‐area [∼(50 μm)2], focused‐ion‐beam implantation of 25 keV Ga+in Si, Ge, InP, InSb, and ZnSe was investigated by experiments and by computer simulations. Specifically, the Ga concentration was determined for implantation fluences Φ ranging from 1×1014to 3×1017Ga+ions/cm2by means of secondary‐ion mass spectrometry. In all materials the Ga peak concentration exhibits an essentially linear increase with fluence up to some 1016cm−2; for higher values of Φ the Ga concentration tends to saturate. The saturation content of Ga at the surfacec∞ranges from ∼2 at % for ZnSe to ∼40 at % for Si. These values appear roughly inversely correlated with the specimens’ sputtering yields and agree thus with the predictions of a model of ion retention in the presence of concurrent sputter erosion. The computer simulations with the dynamic binary‐collision‐approximation codet‐dynproduce a fluence‐dependent evolution of the Ga concentrations in the examined semiconductors which is in qualitative agreement with the experiments. Furthermore, partial sputtering yields and the most probable ranges for 25 keV Ga+impact on the different materials have been determined both experimentally and from the simulation output.

ISSN:0734-211X    

DOI:10.1116/1.587978

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Plasma‐induced etch damage often degrades the electrical and optical performance of III–V high‐density integrated circuits and photonic devices. We have investigated the etch‐induced damage of electron cyclotron resonance (ECR) generated plasmas on the electrical performance of mesa‐isolated GaAspn‐junction diodes. Cl2/Ar, BCl3/Ar, Cl2/BCl3/Ar, and SiCl4/Ar ECR plasmas at ion energies ranging from 10 to 200 eV were studied. Diodes fabricated under low dc‐bias (≤100 V) etch conditions yielded low reverse‐bias currents which were comparable to wet‐chemical‐etched devices. As the dc bias was increased, the diodes showed significantly higher reverse‐bias currents indicating plasma‐induced sidewall damage of thepn‐junction. Variations in diode reverse‐bias leakage currents are reported as a function of plasma parameters and chemistries.

ISSN:0734-211X    

DOI:10.1116/1.587980

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Scanning force microscopy was used to investigate the morphology and the microroughness of the dry etched surfaces of titanium masks and InP substrates. The influence of different ion beam etching procedures on the surface roughness has been studied. Since the observed surface structures were on the nanometer scale, sharp microtips with an improved geometry were used in order to obtain high lateral and vertical resolution. The tips were produced by electron‐beam‐induced deposition employing a field emission scanning electron microscope. Tip convolution effects were considered and, moreover, a scan artifact at steep surfaces features was revealed.

ISSN:0734-211X    

DOI:10.1116/1.587981

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Extremely smooth GaAs surfaces are attained after SiCl4reactive ion etching by preparing the surface before etching with hydrogen plasma exposure to selectively remove the native surface oxides. Using this hydrogen plasma pretreatment, the surface morphology after etching is equivalent to that of the original surface since the etching proceeds uniformly through the GaAs without micromasking effects from a nonuniform surface oxide. The beneficial effects of the hydrogen plasma processing are observed in two different reactors and are found to be independent of the platen temperature during etching. Using atomic force microscopy we find an optimized hydrogen plasma process produces an etched surface morphology with an average surface roughness of 0.9–1.5 nm, as compared to the surface roughness of 0.6 nm before etching or as great as 11.8 nm after etching without the hydrogen plasma pretreatment.

ISSN:0734-211X    

DOI:10.1116/1.587982

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We present a high‐resolution, damage‐free etching technique for GaAs and related compound semiconductors which utilizes surface‐specific photochemistry at 193 nm to excite a physisorbed layer of Cl2on a cryogenically cooled (∼140 K) sample. Etch rates as high as 0.25 Å/pulse (corresponding to 0.09 μm/min) have been achieved. Etching is anisotropic, and etched features of 0.2–0.3 μm linewidth have been routinely obtained. The etch rate has been characterized as a function of several ‘‘system’’ parameters including Cl2‐partial pressure, substrate‐temperature, laser repetition rate and fluence, and the addition of rare gases. A phenomenological model of this cryoetching has been developed which agrees well with the experimental data. The etch damage and contamination have been studied with Auger electron spectroscopy, photoluminescence, and Schottky‐barrier measurements. All results indicate that there is minimal if any damage induced by the cryoetching process.

ISSN:0734-211X    

DOI:10.1116/1.587983

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We present in this article a simple and economic gas line designed for low vapor pressure metalorganic sources introduced into a chemical beam epitaxy chamber without carrier gas. This gas line was tested with triethylgallium and trimethylindium for the growth of GaAs and InP layers. The high conductance of the line allowed minimizing the heating of the source and reaching growth rate as high as 12 μm/h for GaAs. The lower InP growth rate was attributed to the higher viscosity of trimethylindium compared to triethylgallium.

ISSN:0734-211X    

DOI:10.1116/1.587985

出版商:American Vacuum Society    

年代:1995

数据来源: AIP