摘要:

The status of research on both wurtzite and zinc‐blende GaN, AlN, and InN and their alloys is reviewed including exciting recent results. Attention is paid to the crystal growth techniques, structural, optical, and electrical properties of GaN, AlN, InN, and their alloys. The various theoretical results for each material are summarized. We also describe the performance of several device structures which have been demonstrated in these materials. Near‐term goals and critical areas in need of further research in the III–V nitride material system are identified.

ISSN:1071-1023    

DOI:10.1116/1.585897

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Hydrogen ion cleaning procedures of InP(100) surfaces have been studied and the effect of hydrogen on carbon and oxygen contaminations were particularly investigated. The induced structural surface modifications were studied by x‐ray photoelectron spectroscopy andinsitureflected high‐energy electron diffraction just after ion bombardment and after annealing under an arsenic overpressure. Results show that cleaning with hydrogen ions leaves an indium‐rich surface layer on the InP surface. After hydrogen ion bombardment, structural changes of the surface occur and their irreversibility after As stabilization depends on the hydrogen dose. If this dose does not exceed a critical value of about 3×1016ions/cm−2, the structural properties of the InP surface can be restored after thermal annealing under arsenic overpressure. However, both unannealed and annealed surfaces show a strong pinning of the Fermi level, with the creation of defects 0.25 eV below the minimum conduction band, which indicates poor electronic properties always after hydrogen ion bombardment.

ISSN:1071-1023    

DOI:10.1116/1.585898

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A Fe–Ge alloy was used to fabricate a liquid metal ion source (LMIS) for our focused ion beam system. The iron ion and germanium ions can be utilized to create semi‐insulating regions for device isolation andn‐type doping in InP. The properties of the Fe–Ge LMIS were characterized by measuring the ion current‐extraction voltage characteristics, the mass spectrum of the ion species in the ion beam, and the stability of the source current. The changes of resistivity in InP before and after Fe++implant and after thermal annealing were measured in mesa‐etched four‐terminal test structures. The resistivity of as‐implanted samples increases about four orders of magnitude compared with original resistivity. After rapid thermal annealing at 400 °C for 10 s, the resistivity is about two times larger than that of as‐implanted sample.

ISSN:1071-1023    

DOI:10.1116/1.585899

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

In order to optimize the fabrication ofn+–pInP solar cells made by closed‐ampoule diffusion of sulfur intop‐InP:Cd substrates, we have investigated the influence of diffusion conditions on sulfur diffusion profiles. We show that S diffusion in InP is dominated by the P vacancy mechanism and is not characterized by a complementary error function as expected for an infinite source diffusion. The S diffusion mechanism inp‐InP is qualitatively explained by examining the depth profiles of S, P, and In in the emitter layer and by taking into account the presence and composition of different compounds found to form in the In–P–S–O–Cd system as a result of diffusion.

ISSN:1071-1023    

DOI:10.1116/1.585900

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

An analytical solution for the minority carrier concentration in the base region of an emitter–base–emitter contact topology heterojunction bipolar transistor has been developed. This solution is used to calculate various base current components, including the mesa surface recombination current which is geometry dependent. This mesa surface recombination current affects the efficiency with which the injected carriers from emitter traverse the base and reach the collector. The significance of this mesa surface recombination current is evaluated and the current gain is calculated as a function of device geometry and base doping level. In particular, the effect of this mesa surface recombination is examined for devices specifically designed for high frequency applications. The emitter crowding is also analyzed quantitatively and its effects on device current gain are discussed.

ISSN:1071-1023    

DOI:10.1116/1.585857

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Surface contaminations on GaAs (100) wafers have been analyzed by means of temperature‐dependent and angle resolved x‐ray photoelectron spectroscopy (TOXPS, ARXPS), and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS). First, the dependence of the composition, chemical state, and diffusion behavior of the passivating thermal oxide on different annealing temperatures was investigated. The phases of this oxide can be described by a multilayer model and are consistent with the Ga–As–O equilibrium phase diagram. Second, the nature and amount of impurities at ambient and elevated temperatures was studied. No metal contaminants were found within the sensitivity of TOF‐SIMS. The residual amount of carbon contamination at the desorption temperature of the oxide depends on the amount of photon irradiation at ambient temperature.

ISSN:1071-1023    

DOI:10.1116/1.585858

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The surface chemistry of HgCdTe is investigated with regard to the combined effects of etching, photochemical oxidation, and exposure to acids. The potential of angle‐resolved x‐ray photoelectron spectroscopy is utilized to characterize the surface region of the processed compound semiconductor with respect to its compositional depth profile. Upon exposure to the acids HNO3, HCl, H2SO4, and lactic acid, the HgCdTe surface does not degrade but becomes chemically passivated by the coverage of up to a monolayer of a native oxide. By such acid treatments, a residue to elemental tellurium, typically present after the Br2/methanol etching process, cannot be removed but becomes partially oxidized. However, the removal of this Te residue is made possible by the employment of a photochemical oxidation step between the etch and the acid treatment. Upon the formation of the photochemical oxide layer, the substrate composition below the interface is not affected. During the oxidation process, HgO segregates to the surface, leaving a Hg deficient oxide region in the bottom part of the layer.

ISSN:1071-1023    

DOI:10.1116/1.585859

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Polysilicon etch rates and polysilicon‐silicon dioxide selectivities have been measured in a collimated electron cyclotron resonance (ECR) chlorine discharge as a function of microwave power, pressure, gas flow rate, O2addition, and substrate position. High chlorine flow rates, moderate input microwave power, and reduced wafer separation from the ECR plane were found to provide simultaneous high polysilicon etch rates and high polysilicon‐oxide selectivities. The addition of a small amount of oxygen to the chlorine plasma establishes an etch‐deposition competition which can increase the polysilicon‐oxide etch selectivity. Polysilicon etch rates of 4000–5000 Å/min are obtained in combination with stable polysilicon‐oxide etch selectivity values of 50–150 and polysilicon‐resist selectivities of 13–15, using 150 sccm Cl2, 0.6% O2, 3 mTorr total pressure, and 700 W input microwave power. The etched profiles are anisotropic with residue‐free surfaces.

ISSN:1071-1023    

DOI:10.1116/1.585860

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Charging damage of thin gate oxides is often a concern in plasma processing. This study examines the breakdown voltage characteristics of thin gate oxides in low‐energy argon plasmas. An electron cyclotron resonance (ECR) system with a rf‐biased electrode was used. The effects of rf bias, plasma exposure time, and gate oxide thickness on the gate oxide breakdown voltage were measured. The results show that the ECR plasma process with low, self‐induced dc bias does not induce any charging damage for gate oxides as thin as 120 Å. More device failures are produced with higher bias and longer plasma exposure, while thicker gate oxides show less damage.

ISSN:1071-1023    

DOI:10.1116/1.585861

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Molecular oxygen adsorption on several ternary silicides (Ti4M4Si7, M=Ni,Co) and (TiFeSi2) is studied using photoemission. The valence band spectrum shows that the O2dissociates on adsorption and suggests that an exposure of a few hundred langmuirs is sufficient to completely cover the surface with a layer of atomic oxygen. Si 2pcore‐level spectra show that oxygen bonds with the silicon and photoemission peaks from all oxidation states of silicon are observed. 3pcore levels from the metallic elements like titanium do not show core‐level components indicating the formation of metal–oxygen bonds. The bonding of oxygen to silicon could be due to silicon termination of the surface or maybe due to energetics which favor silicon–oxygen bond formation over metal–oxygen bond formation, the breaking of silicon–silicon bonds rather than silicon–metal bonds or the breaking of the fewest atomic bonds.

ISSN:1071-1023    

DOI:10.1116/1.585862

出版商:American Vacuum Society    

年代:1992

数据来源: AIP