Morphological studies on selective growth of GaAs

An alternative approach to the calculation of the four‐probe resistance of nonuniform resistivity structures is presented. This approach is based upon two simplifications in the form of the four‐probe resistance integral. The first arises from the integral's being independent of the probe current density as well as the probe radius. The second simplification involves the rewriting of the integral as one involving only the kernel (without any Bessel functions) and with finite limits which depend only upon the probe spacing. The form of these limits is determined by the analytic calculation of the four‐probe resistance for the case of a semi‐infinite slab. For the case of a uniform layer over an insulating or conducting boundary, the simplified integral leads to analytic expressions for the four‐probe resistance which are compared with the more extensive technique and are also investigated as a function of the probe spacing. For nonuniform resistivity structures, the simplified integral can be easily evaluated by means of the Newton‐Cotes numerical procedure. For general multilayer cases, the results obtained from the Newton‐Cotes method are compared with those obtained from more extensive numerical techniques and are shown to be in excellent agreement. This allows for a vastly simplified implementation of the previously proposed spreading resistance calibration technique.

“…For the situation where x/S > 1, the hyperbolic functions contained in Eq. [7] and [8] may be replaced by exponentials of the same argument. Then P lim Z(x, S) -…”

Section: Derivationmentioning

confidence: 99%

An Alternative Approach to the Calculation of Four‐Probe Resistances on Nonuniform Structures

Albers

Berkowitz

1985

“…Lateral epitaxial growth over oxide or metal mask films formed on crystal substrates has recently developed into an attractive technique for fabricating such new devices as permeable base transistors (PBT's) (1-3) and optical wave guides (4). To date, many reports on the lateral growth of GaAs (1)(2)(3)(4)(5)(6)(7)(8)(9), Si (10,11), and InP (12) over metal or oxide mask films have been published.…”

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confidence: 99%

Lateral Growth Process of GaAs over Tungsten Gratings by Metalorganic Chemical Vapor Deposition

Asai

Ando

1985

Lateral epitaxial growth of normalGaAs over tungsten gratings with 5 μm wide lines and spaces on (001) normalGaAs substrates is performed using metalorganic chemical vapor deposition. A study is made of the dependence of facet shapes and growth rates of the overgrown layers on grating direction, growth temperature, and arsine false(AsH3false) and trimethylgallium (TMG) flow rates. From the perspective of crystallography, all the facets observed in the overgrown layers were found to be classified into four individual groups: {110}, {}As, {1̅12}As, and {113}Ga faces. The normalGaAs opening direction on the (001) substrate surface is found to be the most essential parameter for determining the crystallographic planes of the facets. Other important controlling parameters for the facet formation are the growth temperature and partial pressure of AsH3 . The partial pressure of TMG has no influence on the faceting growth. On the other hand, the overall growth rate of the overgrown layer is limited only by the TMG flow rate. These results can be qualitatively explained by the Langmuir‐Rideal model.

“…The GaAs under these windows may be etched to form troughs into which epitaxial GaAs is inlaid or the GaAs may be epitaxially grown on the original substrate surface to form low profile mesa structures. The epitaxy technologies that have been considered are liquid phase epitaxy LPE (1)(2)(3)(4), vapor phase epitaxy VPE (5)(6)(7)(8)(9)(10), and molecular beam epitaxy MBE (11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In MBE, the growth is by impinging thermal energy beams of atoms or molecular species such as As4 or As2 onto the heated substrate.…”

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confidence: 99%

Aspects of GaAs Selective Area Growth by Molecular Beam Epitaxy with Patterning by SiO2 Masking

Cheng

Milnes

1983

The selective epitaxy of GaAs through windows in SiO2 deposited on semi-insulating GaAs substrates has been studied. Etching of the (100) substrates for planar inlaid deposition may incur problems of irregular nonfiat-bottomed profiles to the troughs, and problems of voids after deposition because of the SiO~ undercutting. It is shown that flat-bottomed holes may be obtained by use of an etch of composition l I~ SO4:2.5I-$ O2:50H20 and that this has a suitable etch rate. The problem of voids because of SiO~ undercutting may be solved by an extra step that removes the overhangs. Many orientations of patterns were studied on the substrates to confirm the effectiveness of the recommended procedures.