ISSN:0734-211X    

DOI:10.1116/1.582511

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The paper discusses likely future developments in heterostructure bipolar technology, especially by MBE. This written version concentrates on two new conceptual developments extending earlier concepts. One of these pertains to the problem of emitter/base junction grading. A grading scheme is proposed that extends the grading through the base region and creates a graded‐gap base. The other proposes an extension of permeable base transistor technology to bipolar transistors in what is called a gridded‐base bipolar transistor. Both promise a further increase in device speed, largely by addressing themselves to the persistent problem of base resistance reduction. Several other topics, already contained in the author’s January 1982 review paper and presented orally at the Workshop, have been omitted from this printed version.

ISSN:0734-211X    

DOI:10.1116/1.582513

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Molecular beam epitaxy can fill most of the requirements for high speed III–V compound semiconductor devices. Precise compositon and doping profiles, such as those in selectivity doped heterojunction transistors (SDHT) are examples. The inverted SDHT with the Al,GaAs under the GaAs is a future requirement. High quality, Al,GaAs buffer layers are a general requirement. Conduction band engineering, away from the active layer needs inventive research. The role of the superlattice or other means of improving the buffer needs effort. InP or Al,InAs buffer or confinement layers also need effort, along with improved GaInAs. The requirements of short, ballistic electron FETs, ballistic heterojunction GaAs bipolar transistors, and ballistic injecting and drift transistors will also be reviewed. High current density, exceeding 105A/cm2, for very high frequency and speed, requires new levels of MBE performance for Ohmic contacts also. The relative merits of GaInAs and GaAs as active materials for high speed devices will also be covered, including applications to high speed photodetectors.

ISSN:0734-211X    

DOI:10.1116/1.582514

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Refractory oxide films of Al2O3, SiO2, MgO, and Al2MgO4have been grown in a molecular beam epitaxy (MBE) system using As2O3and Sb2O3as the oxygen source. On the growth surface, elements such as Al whose oxide is more stable than the group V oxide will reduce the group V oxide and form a refractory oxide. With the growth temperature held above 350 °C the group V oxide is volatile and therefore will not be appreciably incorporated into the film as verified by ESCA measurements. This technique allows for MBE growth of oxides with low background pressures because the group V oxides stick well to the liquid nitrogen cooled cryopanels. Metal–insulator and semiconductor–insulator superlattices are possible by opening and closing the group V oxide cell shutter. The wide variety of oxide films possible with this technique could find applications to microwave, optical, magnetic, and display devices.

ISSN:0734-211X    

DOI:10.1116/1.582515

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Small amplitude periodic compositional variations in the growth direction have been observed in GaxIn1−xAs and AlxIn1−xAs layers grown by MBE with a rotating substrate holder in transmission electron microscopy (TEM) studies. The period of these compositional oscillations has been correlated with the substrate rotation frequency. These oscillations have been attributed to the small variations in the flux profile of the group III elements over the substrate area. Sharp peaks obtained in x‐ray diffraction studies indicate the absence of compositional grading in the growth direction, despite these oscillations.

ISSN:0734-211X    

DOI:10.1116/1.582518

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.582519

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The third order nonlinear susceptibility χ(3)due to band nonparabolicity is investigated for gallium arsenide–aluminum arsenide superlattices. Optimization of well width, superlattice period, and barrier height give rise to large nonparabolicities which yield nonlinear susceptibilities comparable to those of bulk indium antimonide and two orders of magnitude larger than those of bulk gallium arsenide.

ISSN:0734-211X    

DOI:10.1116/1.582520

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The formation of a GaSb–AlSb superlattice grown by molecular beam epitaxy has been demonstrated metallurgically from x‐ray diffraction and optically from electroreflectance and photoluminescence measurements. The luminescence spectra exhibit emission peaks associated with interband transitions between quantum states as well as acceptor impurities.

ISSN:0734-211X    

DOI:10.1116/1.582521

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Data are presented on a series of consecutively grown superlattices with different layer thicknesses. For each sample, the ratio of the GaAs layer thickness to the AlAs layer thickness was kept constant. In addition, the total thickness of the superlattice was the same for each sample, resulting in a set of samples differing only in the number and separation of AlAs–GaAs interfaces. Photoluminescence from these structures shows an initial intensity drop followed by a substantial intensity increase as the layer thicknesses are decreased. Data are also presented on a series of samples grown consecutively under identical growth conditions, with the exception that the substrate temperature was varied between 580 and 725 °C. Photoluminescence from these superlattices indicates the optimum growth temperature is in the region of 640–670 °C, where the photoluminescence intensity is a factor of 50 greater than for samples grown at lower temperatures. A calibration method, relating indicated growth temperature to actual growth temperature is described.

ISSN:0734-211X    

DOI:10.1116/1.582522

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

MBE GaAs/Al0.3Ga0.7As superlattices have been examined by Auger electron spectroscopy (AES) using Ar+sputter depth profiling and line scans across the crater wall left after depth profiling. The superlattice was grown by MBE with ten periods of alternating Al0.3Ga0.7As and GaAs layers of 200 and 50 Å thickness, respectively, at a substrate temperature of 700 °C. AES sputter depth profiling clearly indicated the periodic nature of the structure through all ten periods, although the Al signal did not appear to drop to zero in the GaAs layers, probably due to sputter effects. The use of the standard elemental Auger sensitivity factor for Al (0.070 at 5 kV) yielded the correct atomic concentration of Al in the Al0.3Ga0.7As layers (15% forx=0.3), however, this was not true for either Ga or As. By using an AES line scan up the sputter crater wall, the superlattice layers were spread out by a factor of ∼2400. The periodicity of the structure was more strongly evident than that seen by AES depth profiling with the Al signal dropping to zero in the scanned crater wall regions corresponding to the 50 Å GaAs layers. The expanded superlattice was also examined by absorbed current and secondary electron imaging and by AES mapping.

ISSN:0734-211X    

DOI:10.1116/1.582523

出版商:American Vacuum Society    

年代:1983

数据来源: AIP