摘要:

A low‐temperature annealing process has been developed for the fabrication of low resistivity ohmic contacts to very thin (<0.2 &mgr;m)n+GaAs epilayers. It is shown that by altering the relative amounts of Ni in the commonly used AuGe/Ni/Au contact system, the anneal temperature can be reduced from the standard 420–450 °C to 320 °C or less without deterioration in specific contact resistance. The specific contact resistances were evaluated using the modified transmission line model.

ISSN:0003-6951    

DOI:10.1063/1.96632

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The electro‐optic effect has been investigated in a GaAs/AlGaAs multiquantum well waveguide structure 50 meV from the excitonic transition. We extractr41=−1.6×10−10cm/V and (R11−R12)=6×10−16cm2/V2, nonlinear optical characteristics that differ from homogeneous GaAs layers. This (R11−R12) value is similar in magnitude but opposite in sign to that found in InGaAsP 130 meV from the band gap.

ISSN:0003-6951    

DOI:10.1063/1.96633

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The recombination kinetics of charged carriers in GaAs have been investigated on a picosecond time scale. A pump‐probe technique was used to measure reflectivity changes as a function of time up to 900 ps. Initially, (1.2±0.2)×1020carriers/cm3were excited into the conduction band. The decay curve indicated dominance of a three‐body (Auger) recombination process up to about 120 ps, with two‐body recombination processes dominating after 120 ps, the switch occurring at a carrier concentration of (5±2)×1019carriers/cm3. Values for the Auger recombination coefficient and the two‐body recombination coefficient were determined to be (7±4)×10−31cm6 s−1and (3.4±1.7)×10−11cm3 s−1, respectively. The change in reflectance was observed to have essentially returned to zero within 900 ps.

ISSN:0003-6951    

DOI:10.1063/1.96634

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

It is reported that the lattice parameters of a 3‐&mgr;m‐thick [1,0,0] single crystal CdTe epitaxial layer on a [1,0,0] single crystal GaAs substrate behave anomalously below 120 K. The epilayer used in this experiment was deposited at 410 °C by metalorganic chemical vapor deposition. This x‐ray lattice parameter study was done in the temperature range between about 8 and 300 K. Our results show that the lattice parameters perpendicular to the surface of both the GaAs substrate and the CdTe epilayer shrink four times more than the corresponding bulks when the samples are cooled down to 10 K. It is further seen that there is no compensation effect between the elements of the composite system; that is, the lattice parameters of the two materials change in the same direction as if the composite system—the epilayer and the thickness of the substrate which is probed by the x rays—would behave as a new material with entirely new physical properties.

ISSN:0003-6951    

DOI:10.1063/1.96635

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Unusual metastable and polarization behavior has been observed for Al0.48In0.52As/ Ga0.47In0.53As avalanche photodiodes by capacitance spectroscopy. The metastability arises from interplay of the heterojunction barrier with defects in the Al0.48In0.52As layer. Defect occupation controls the reverse bias characteristics of the device while the heterojunction presents a barrier to carrier capture by the defects.

ISSN:0003-6951    

DOI:10.1063/1.96636

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report the isolation of a new defect inn‐type silicon following room‐temperature electron irradiation. Using deep level transient spectroscopy (DLTS) combined with minority‐carrier injection at 250 K, we show that the DLTS peak usually ascribed to the phosphorus‐vacancy pair hides a signal arising from this defect in its stable configuration. We find that the defect can exist in three other configurations which can be individually studied by DLTS. It is proposed that this defect involves a lattice vacancy and a phosphorus atom, plus a third unidentified defect or impurity.

ISSN:0003-6951    

DOI:10.1063/1.96669

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The maximum frequency at which amplification can be obtained from quantum well oscillators is discussed. Intrinsically, the frequency limit for having negative differential resistance (NDR) can be very high, of the order of the inverse of the electron transit time. Owing to the large capacitance of the well and barrier regions, the actual frequency limit at which amplification occurs may be lower than the intrinsic limit because of the capacitance charging time. We have estimated the frequency limit of NDR by considering the electron transit time and have calculated the maximum oscillation frequency from an equivalent circuit model. We have also obtained an expression for the high‐frequency power output as a function of frequency, based on a transmission line model.

ISSN:0003-6951    

DOI:10.1063/1.96617

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This letter describes the preparation and electrical characteristics ofa‐Si:Hp‐i‐n‐i‐pandn‐i‐p‐i‐nthin‐film diodes suitable for driving monochrome liquid crystal displays with more than 500 lines. The symmetrical current‐voltage curves in the reverse breakdown regime can be described byi=i0 exp(E/E0), whereE0&bartil;9×104V/cm. In the range 20–125 °C, the current is thermally activated with an energy of 0.25 eV. The response time to applied voltage pulses is ≤10 &mgr;s. The stability of the electrical characteristics is adequate for at least 104h of operation in a liquid crystal display. Electrical characteristics indicate that the reverse breakdown current is a tunneling current injected into theilayer and that electrons are likely to be dominant.

ISSN:0003-6951    

DOI:10.1063/1.96618

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We report on comparative photoluminescence (PL) studies of GaAs/Al0.33Ga0.67As single quantum well structures grown via molecular beam epitaxy underidenticalgrowth conditions employing (a) customary practice ofnogrowthinterruptionand (b)growthinterruption. The growth conditions themselves are chosen to be near optimum, as determined from the growth kinetics exemplified by the reflection high‐energy electron diffraction intensity dynamics. Results show PL lines with fine structure and widths among the narrowest ever reported for 28.3 and 56.6 A˚ wells. The fine structure is indicative of kinetically controlled interfaces with a predominant step height of one atomic layer and the linewidths a first measurement of intrinsic alloy disorder scattering.

ISSN:0003-6951    

DOI:10.1063/1.96619

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Limited reaction processing was used to deposit ultrathin, highly doped layers of epitaxial silicon. Multilayer structures consisting of alternating undoped and heavily boron‐doped regions were fabricatedinsitu. The interlayer doping profiles of these structures, as determined by secondary ion mass spectroscopy, are abrupt. Van der Pauw measurements indicate that the electrical characteristics of thep+epitaxial films are comparable to bulk material.

ISSN:0003-6951    

DOI:10.1063/1.96620

出版商:AIP    

年代:1986

数据来源: AIP