The Detection of Structural Defects in Indium Phosphide by Electrochemical Etching

The photoelectrochemical oxidation of (i00), (I 11), and (i 11) n-InP and n-GaAs in several acidic solutions has been investigated. Specific interactions between the single crystal semiconductors and solvent selectively revea_l_crystal faces other than those originally exposed to the solvent. The relative stability of the n-lnP faces is (111) > ( 100) > ( 111). The first case of electron injection during the photoanodic dissolution of III-V compound semiconductors has been observed with (I 00) and ( 111) n-InP. Nucleophilic attack by Cl-or Br-produce intermediates whose potential and kinetics allow electron injection into the semiconductor conduction band reducing the number of photons required for the reaction from six to four. The conditions for selectively etching smooth surfaces on (100) n-lnP are discussed in detail along with the conditions for maintaining polished surfaces on n-lnP(lll) or A-face, which is difficult with conventional chemical polishes.

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

The Photoelectrochemical Oxidation of (100), (111), and (1̅1̅1̅) n ‐ InP and n ‐ GaAs

Kohl¹,

Wolowodiuk²,

Ostermayer³

1983

“…Figure 10 shows a typical SEM micrograph of a hollowedout grappe feature observed on a {110} unetched cleavage face. surface has been proposed by Elliott and Regnault (10).…”

Section: X-ray Topography Of Inclusionsmentioning

confidence: 99%

A Study of Inclusions in Indium Phosphide

Augustus¹,

Stirland²

1982

A detailed examination of unusual inclusions in InP substrates has been undertaken. Techniques employed have included optical microscopy, scanning electron microscopy, reflection and transmission x-ray topography, conventional and high voltage electron microscopy, electron diffraction, energy dispersive x-ray analysis, and Auger emission spectroscopy. Inclusions have been detected in many, but not all, undoped, Fe-, Sn-, and Ge-doped InP ingots, at densities from -I0 "~ to I04 cm-'-'. Larger inclusions consist essentially of a central core of densely tangled dislocations, surrounded by dislocation loops predominantly on {ll0} planes and extending I0-20 ~m outwards from the core. The entire complex of core plus surrounding loops results in a characteristically pitted appearance after etching, or as a region of strong contrast by x-ray topography. Smaller inclusions (-i ~m size) have been examined in electron microscope specimens foils. Some inclusions have been found at line dislocations, and it is probable that this is where the majority of inclusions originate, by a nucleation process. Attempts to determine the structure and chemical composition of the inclusions are presented and discussed.Single crystal indium phosphide is assuming increasing importance in at least three different areas of semiconductor technology. Iron-doped semi-insulating substrates with resistivities > 107 12cm are required for fabrication of indium phosphide FET's. n -T y p e substrates, usually produced by tin-doping to give carrier concentrations ,-, 1017-10 is cm -3, are required on which to grow epitaxial layers for transferred electron microwave devices. Finally, indium phosphide substrates are necessary for the growth of lattice p a r a m e t e r matched t e r n a r y (GaInAs) and quaternary (GaInAsP and GaAlInAs) epitaxial layers for various opto-electronic devices, particularly lasers, high brightness diodes, and detectors in the 1.3-1.6 ~m region.

“…Chemical etching is the simplest method for revealing dislocations and other defects in crystals. A number of papers have been published recently dealing with chemical, electrochemical, and photochemical etching of InP (7)(8)(9)(10)(11), InGaAs (12,13), and InGaAsP grown on <111> B InP (14,15). However, the <100> orientation is widely utilized for LED's, lasers, and other devices, but no chemical etchant that selectively reveals dislocations in <100> InGaAsP layers has yet been reported.…”

mentioning

confidence: 99%

A Defect Etchant for <100> InGaAsP

Lourenço

1984

A defect revealing etching technique for normaln‐normalInGaAsP grown on <100> normalInP by LPE is reported. A chemical solution used with illumination produces protrusions in thin quaternary layers, which correlate well with dislocation pits in underlying and overlying normalInP layers. Using the new etchant, an increase in defect density in the active layer over the defect density in the buffer layer has been detected in lattice matched (≲0.04%) normalInGaAsP/normalInP LED structures.