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An apparatus is described for the vapor‐solid diffusion of donors and acceptors into silicon at atmospheric pressure. It consists essentially of a fused silica tube extending through one or more controlled temperature zones. A gas such as nitrogen carries the vapors from the heated impurity element or one of its compounds past the heated silicon.At temperatures above about 1000 °C, gases such as helium or nitrogen are shown to cause serious pitting or erosion of the silicon surfaces. A thin vitreous silicon dioxide envelope enclosing the silicon during the high temperature heating operation is shown to provide complete protection of the underlying surface against damage. Methods of obtaining surface passivation are described.In addition to surface protection, a silicon dioxide surface layer also is shown to provide a selective mask against the diffusion into silicon of some donors and acceptors at elevated temperatures. Data are presented showing the masking effectiveness of the silicon dioxide layer against the diffusion of several donors and acceptors into silicon.The application of the masking technique to produce precise surface patterns of both n‐ and p‐type is described. An example of its feasibility in device considerations is illustrated by the construction of a transistor by double diffusion. This transistor is unique in that both the emitter and base contacts are made at the surface in adjacent areas.Finally a new predeposition technique is described for controlling the impurity levels in diffused layers over wide ranges. Data are presented to illustrate this technique.

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Single crystals of normalGaP have been grown from the vapor phase in an open tube process on seeds of either normalGaP or normalGaAs . The reaction between H2O and a normalGaP source above 700°C in a stream of H2 provides the vapor phase species which react upon cooling to deposit normalGaP crystals. Epitaxial layers of normalGaP have been grown on substrates at temperatures as low as about 700°C, but the growth rates are extremely small. Substrate temperatures of about 1000°–1080°C and source temperatures of 1100°C generally were employed in this investigation to obtain reasonable growth rates for the production of large single crystals. Single crystals of normalGaAs and solid solutions of GaPxAs1−x also have been grown by this method. The growth conditions, crystal morphology, crystal properties, doping, and growth from the elements are discussed.

Two special open-tube furnace systems, respectively containing all fused silica and all alumina furnace-area components, and in which P is supplied through the reaction of wet H2 with AlP to form PH3, have been constructed for the growth of GaP crystals from Ga solution. Careful attention has been paid to the purification of the PH3 and H2 transport gas. Unwanted contamination from the flow tubes and furnace area has been minimized. The crystals are then suitable for the controlled study of the optical properties of the impurities C and Si, persistent residual impurities in GaP crystals grown under less stringent conditions. The residual concentrations of S and N have also been dramatically reduced in this system. Clearly defined chemical evidence indicates that carbon rather than silicon is the shallow acceptor (ionization energy EA ∼48 meV) in the residual green donor-acceptor pair luminescence spectrum in GaP. Analysis of sharp line donor-acceptor pair transitions observed at the high-energy tail of a broad red luminescence band (peak energy ∼1.96 eV) characteristic of silicon-doped crystals indicates that silicon is a deep acceptor (EA∼204 meV) on P lattice sites and a shallow donor (ED∼80 meV) on Ga lattice sites in GaP. Sharp line green spectra observed for recombinations at C–Si and Zn–Si pairs confirm this value of (ED)Si. The shallow green pair transitions involving Si donors are strongly coupled to ∼17.5 meV and ∼29 meV low-energy phonons, unlike pair recombinations involving P site donors. This marked difference in phonon coupling invalidates judgment of the relative values of ED for S, Te, and Si donors from the relative positions of the peak intensities of the green or red pair spectra involving these donors. Small shifts in the no-phonon discrete pair lines between crystals doped with Si28 and Si30 confirm the suggested role of Si in these spectra.

We report the infrared radiative recombination of electrons bound to deep O donors with holes bound to C, Zn, or Cd acceptors in GaP. From the transition energies of the discrete no-phonon lines, which can be closely accounted for using a simple Coulomb donor-acceptor interaction energy term, the ionization energy of the O donor is calculated to be 893±2 meV. Aggregation between Zn (or Cd) acceptors and O donors in nearest-neighbor lattice sites produces strong red luminescence not observed in C-doped crystals where the closest possible donor-acceptor pairs are next-nearest neighbors. The infrared pair spectra are broad because of strong phonon-assisted transitions arising from the tight binding of the O donor. Two modes of energy 19.5 and 47.0 meV are prominent in the infrared spectra, whereas only one ^48-meV mode is prominent in the green luminescence due to recombinations between shallow donors and C, Zn, or Cd acceptors in GaP.