摘要:

A photocontrolled InGaAs/AlAs double‐barrier resonant‐tunneling diode, for the first time, has been demonstrated. The photoinduced valley current in the resonant‐tunneling diode was optically controlled by varying the incident optical power level. With the incident optical power intense enough, the photogenerated valley current became dominant over the peak current. As a consequence, the negative differential resistance of the device was nullified. A photogeneration process, based on photogenerating carriers in the depletion region adjacent to the double barriers, is described and characterized. The device under illumination was modeled as a resonant‐tunneling diode in series integration with a photodetector. The quantum efficiency for the photogeneration was measured and found comparable with theoretical prediction. The demonstrated photocontrolled double‐barrier resonant‐tunneling diode can be useful in a variety of applications.

ISSN:0734-211X    

DOI:10.1116/1.587019

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Segregation of Si in molecular beam epitaxy grown GaAs quantum wells is investigated using current–voltage characteristics (I–V) of quantum well infrared photodetectors. Theoretical modeling is used to derive the extent of segregation from the measured ratio of dark currents through the device in forward and reverse directions. The segregation length, expressed in Å per decade of concentration decay, increases from 12 to 52 Å on increasing the growth temperature from 550 to 605 °C. The character of this increase indicates that Si segregation is kinetically limited in this temperature range, but approaches thermal equilibrium above 600 °C. The effect of arsenic overpressure on the segregation length at a growth temperature of 595 °C is also studied. An increased overpressure of arsenic suppresses Si segregation for both dimeric and tetrameric forms of As. The effect of As2is very small, with the segregation length decreasing from 52 to 48 Å on increasing the arsenic flux by a factor of eight from its nominal value. The same increase in flux gives a much stronger suppression of Si segregation if As4is used: the segregation length decreases from 51 to 40 Å.

ISSN:0734-211X    

DOI:10.1116/1.587020

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We have grown high mobility one‐dimensional electron gases by molecular‐beam epitaxy (MBE) on etched GaAspnpnpfacets. By applying the appropriate bias to thep‐ andn‐GaAs layers which serve as a unique backgate, the electron gas width and mobility may be controlled. The width may be varied between about 400 and 100 nm. We also find that the mobility increases up to about 6×105cm2/V s, rather than decreases with falling carrier concentration.

ISSN:0734-211X    

DOI:10.1116/1.587021

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

High‐radiative recombination efficiency arrays of InGaAs/GaAs strained quantum wires have been fabricated by a combination of e‐beam lithography, dry and wet etching, sidewall desorption, migration‐enhanced epitaxial and molecular beam epitaxial regrowth. The structure was evaluated by reflection high‐energy electron diffraction, cross‐sectional transmission electron microscopy, and photoluminescence spectroscopy. Transmission electron microscopy study showed that a defect‐free regrown layer and excellent sidewall coverage have been attained. From the photoluminescence measurement, the sample showed high‐radiative efficiency, and had strong photoluminescence for wire widths down to 190 nm.

ISSN:0734-211X    

DOI:10.1116/1.587022

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We report the design and demonstration of a novel resonant tunneling device which displays bistability in operating current over a range of applied voltages. The device is based on an InAs/AlxGa1−xSb double barrier heterostructure. Although similar in design to conventional resonant tunneling structures, the type‐II InAs/AlxGa1−xSb heterostructure permits the simultaneous accumulation of electrons and holes in the quantum well/barrier region under an applied bias. The steady‐state free‐charge distribution, and hence the device current, is strongly dependent upon the bias history of the device. This effect is manifested as a current‐controlled (S‐shaped) negative differential resistance under conditions in which the device current is specified while the device voltage is measured; a bistable (hysteretic) characteristic is observed under conditions in which the voltage is specified and the current is measured. We have observed current bistability for AlxGa1−xSb barrier compositions in the range 0.4

ISSN:0734-211X    

DOI:10.1116/1.587023

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Electron beam lithography has been used to investigate the growth of GaAs wires in finely corrugated GaAs. Electron beam lithography was used to define 100 nm corrugations along the [110] and [11̄0]directions; anisotropic etching revealed grooves that were V‐shaped ([11̄0]) or dovetailed ([110]). Here, AlAs resharpens the groove profile during growth, provided the barrier thickness is not less than 30–40 nm. Also, GaAs exhibited an enhanced growth rate in both groove directions, with an increase of 60% over the nonpatterned growth rate for the [11̄0] direction. Growth in grooves along [11̄0]preserved the V shape of the groove, while [110] growth showed evidence of deposition masking and microvoiding.

ISSN:0734-211X    

DOI:10.1116/1.587024

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

High‐quality two‐dimensional electron gases (2DEGs) were regrown ontoexsitupatterned substrates and the effect of the distance between the 2DEG and the contaminated regrowth interface was investigated. At a separation of 220 nm mobilities of 7.1×105cm2 V−1 s−1in the dark and 1.3×106cm2 V−1 s−1after illumination with a red light‐emitting diode (LED) were measured with corresponding carrier concentrations of 2.4×1011and 4.3×1011cm−2. The quality of this 2DEG was equivalent to that attained in conventionally grown 2DEGs at the time, indicating that the 2DEG was not affected by presence of the regrowth interface in this case. For smaller separations a degradation in the 2DEG quality was observed. Thus, at a separation of only 60 nm, a mobility of 4.1×105cm2 V−1 s−1at a carrier concentration of 4.2×1011cm−2was measured after illumination. The use of an independently contactedn+layer in the patterned substrate as a backgate was also demonstrated.

ISSN:0734-211X    

DOI:10.1116/1.587025

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Lateral patterning of a buried GaAs epilayer can be achieved during molecular beam epitaxy growth byinsituimplantation with a high energy focused ion beam. Applying this technique, 30 keV Ga ions have been used to form small, highly resistive, regions in the backgate layer of a double two‐dimensional electron gas (2DEG) structure. Independent contacts to the two 2DEGs were then achieved by selectively depleting out regions of the upper and lower 2DEGs with potentials on patterned front and backgates. In the resulting devices, the magnetoresistance of the two 2DEG layers was measured both together and separately. It was demonstrated that a bias of up to ±50 mV could be applied, across the 20 nm AlGaAs barrier separating the 2DEGs, with leakage currents of<0.01 nA at 4.2 K. Finally, resonant tunneling between the two 2DEGs was observed when the barrier thickness was reduced to 7 nm. These results have demonstrated the success of this novelinsitufabrication route.

ISSN:0734-211X    

DOI:10.1116/1.587026

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We report the comparison studies of molecular beam epitaxial growth of AlGaAs/Ge/GaAs heterostructures on differently oriented GaAs substrates. We have investigated the molecular beam epitaxial growth of Ge on GaAs, and GaAs and AlGaAs on Ge epitaxial layers with the aim of obtaining device‐quality interfaces of AlGaAs and GaAs epilayers on Ge which are free of antiphase domains. Our results show that the junctions grown on (311)B oriented substrates have better electrical characteristics than those grown on (100) oriented substrates. This is due to the absence of antiphase domains and less interface charge in heterostructures grown on (311)B substrates.

ISSN:0734-211X    

DOI:10.1116/1.587028

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The room temperature observation of quantum mechanical reflections of electrons at an aluminum/gallium arsenide Schottky barrier is reported here. Molecular‐beam epitaxy was used to grow an AlAs/GaAs/AlAs double barrier resonant tunneling diode (RTD) followed by an epitaxialinsitugrown aluminum/gallium arsenide Schottky barrier. This RTD was used to inject a nearly monoenergetic beam of electrons towards the Schottky barrier. The measuredI–Vcurves show resonances associated with the reflections of electrons at the Schottky interface. Understanding the transport properties of hot electrons at a Schottky barrier may prove important for understanding the physics of metal base transistors and other device structures that employ the use of epitaxial metals.

ISSN:0734-211X    

DOI:10.1116/1.587029

出版商:American Vacuum Society    

年代:1994

数据来源: AIP