The Growth and Physics of MBE Structures

Low temperature electrical measurements on particular semiconductor structures can exhibit effects due to the spatial confinement of carriers and reduced dimensionality. Examples are provided by studies of tunnelling in confining structures, transport in narrow channels, ballistic transport through constrictions and quantum interference in rings. These observations rely on the growth of layers by molecular beam epitaxy (MBE) to provide both two-dimensional electron gases (2DEGs) and the very high material quality essential for the observation of some quantum effects. To define the specific geometries necessary for the above experiments electrostatic "squeezing" can be used to confine the planar carrier gas to regions of controllable extent. Recent results obtained from MBE GaAs/AlGaAs 2DEG structures can now be compared with measurements made on hole gases and the use of in situ ion beams in fabrication promises a new class of structures for investigation. However, it is rarely sufficient merely for MBE to provide a carrier gas with the highest maximum carrier mobility. The particular requirements of an experiment affect not only the design of the structure itself but also the MBE growth strategy and the optimum deposition conditions. Growth rate, substrate temperature and source material flux ratios are MBE variables and the suitability of layers for specific postgrowth physics experiments can be shown to depend upon these variables in a systematic manner. Moreover, further requirements for the grown material can include the need to provide specific sheet carrier concentrations, high mobilities in unilluminated samples and the complete absence of conducting paths in parallel with the 2DEG. There are often compromises inherent in attempting to simultaneously optimise several MBE variables and careful management of the MBE machine itself is essential.

[1]  E. Linfield,et al.  The effect of low-energy Ga ions on GaAs/AlGaAs heterostructures , 1990 .

[2]  B. Goldberg,et al.  Fractional quantum Hall effect in a high‐mobility GaAs/AlxGa1−xAs multiple quantum well heterostructure , 1989 .

[3]  T. Thornton,et al.  Electrostatically defined heterojunction rings and the Aharonov–Bohm effect , 1989 .

[4]  Ahmed,et al.  Vanishing Hall voltage in a quasi-one-dimensional GaAs-AlxGa1-xAs heterojunction. , 1988, Physical review. B, Condensed matter.

[5]  David A. Ritchie,et al.  The transition from one- to zero-dimensional ballistic transport , 1988 .

[6]  D. Ritchie,et al.  Addition of the one-dimensional quantised ballistic resistance , 1988 .

[7]  D. Lang,et al.  Effect of arsenic source on the growth of high‐purity GaAs by molecular beam epitaxy , 1988 .

[8]  M. Panish,et al.  Ultrathin semiconductor layer masks for high vacuum focused Ga ion beam lithography , 1988 .

[9]  T. Thornton,et al.  One-dimensional transport and the quantisation of the ballistic resistance , 1988 .

[10]  J. Cunningham.  Quantum size effect in d-doped AlGaAs heterostructures , 1988 .

[11]  Williamson,et al.  Quantized conductance of point contacts in a two-dimensional electron gas. , 1988, Physical review letters.

[12]  Scherer,et al.  Quenching of the Hall effect in a one-dimensional wire. , 1987, Physical review letters.

[13]  M. Roukes,et al.  Ultranarrow conducting channels defined in GaAs‐AlGaAs by low‐energy ion damage , 1987 .

[14]  J. Harris,et al.  Wavelength-dependent photoconduction effects on the second sub-band occupancy in (Al, Ga)As/GaAs heterojunctions , 1987 .

[15]  B. Etienne,et al.  Two-dimensional electron gas of very high mobility in planar doped heterostructures , 1987 .

[16]  T. Hiramoto,et al.  One-dimensional GaAs wires fabricated by focused ion beam implantation , 1987 .

[17]  Ahmed,et al.  Universal conductance fluctuations and electron coherence lengths in a narrow two-dimensional electron gas. , 1987, Physical review. B, Condensed matter.

[18]  T. Block,et al.  Substrate rotation and carbon generation in a molecular-beam epitaxy system , 1987 .

[19]  Chang,et al.  Observation of the Aharonov-Bohm effect for omega c tau >1. , 1987, Physical review letters.

[20]  A. Gossard,et al.  GaAs structures with electron mobility of 5×106 cm2/V s , 1987 .

[21]  W. Mckinnon,et al.  Conduction in illuminated GaAs/AlxGa1−xAs heterostructures. I. Experiment , 1987 .

[22]  M. Kawabe,et al.  The origin of a highly resistive layer at a growth-interrupted interface of GaAs grown by molecular-beam epitaxy , 1987 .

[23]  H. Sakaki,et al.  Atomistic models of interface structures of GaAs-AlxGa1−xAs (x = 0.2−1) quantum wells grown by interrupted and uninterrupted MBE , 1987 .

[24]  J. Harris,et al.  Two‐dimensional electron gas structures with mobilities in excess of 3×106 cm2 V−1 s−1 , 1987 .

[25]  Lee,et al.  Universal conductance fluctuations in metals: Effects of finite temperature, interactions, and magnetic field. , 1987, Physical review. B, Condensed matter.

[26]  W. T. Moore,et al.  Measurement of GaAs surface oxide desorption temperatures , 1987 .

[27]  Thornton,et al.  Magnetic depopulation of 1D subbands in a narrow 2D electron gas in a GaAs:AlGaAs heterojunction. , 1986, Physical review letters.

[28]  E. Mendez,et al.  High mobility two‐dimensional hole gas in an Al0.26Ga0.74As/GaAs heterojunction , 1986 .

[29]  G. Stillman,et al.  Reduction of the acceptor impurity background in GaAs grown by molecular beam epitaxy , 1986 .

[30]  H. Hashimoto,et al.  Application of focused ion beam technology to maskless ion implantation in a molecular beam epitaxy grown GaAs or AlGaAs epitaxial layer for three‐dimensional pattern doping crystal growth , 1986 .

[31]  G. J. Davies,et al.  One-dimensional conduction in the 2D electron gas of a GaAs-AlGaAs heterojunction , 1986 .

[32]  H. Sakaki,et al.  Atomic-Scale Structures of Top and Bottom Heterointerfaces in GaAs–AlxGa1-xAs (x=0.2-1) Quantum Wells Prepared by Molecular Beam Epitaxy with Growth Interruption , 1986 .

[33]  L. L. Taylor,et al.  Parallel conduction in GaAs/AlxGa1-xAs modulation doped heterojunctions , 1985 .

[34]  Webb,et al.  Observation of h/e Aharonov-Bohm oscillations in normal-metal rings. , 1985, Physical review letters.

[35]  H. Sakaki,et al.  One Atomic Layer Heterointerface Fluctuations in GaAs-AlAs Quantum Well Structures and Their Suppression by Insertion of Smoothing Period in Molecular Beam Epitaxy , 1985 .

[36]  E. Mendez,et al.  Temperature dependence of hole mobility in GaAs‐Ga1−xAlxAs heterojunctions , 1985 .

[37]  Hiroshi Arimoto,et al.  GaAs Growth Using an MBE System Connected with a 100 kV UHV Maskless Ion Implanter , 1984 .

[38]  K. Heime,et al.  Selectively dopedn-AlxGa1−xAs/GaAs heterostructures with high-mobility two-dimensional electron gas for field effect transistors , 1984 .