Materials Research Papers: Prof. Glenn H. Chapman

This page contains the paper abstract and full PDF versions of publications on materials research (Pentenary Semiconductors, CdS) which are not connected to other projects (see also inorganic thermal resist papers). Papers in this section are connected to my PhD research in I(b)-III-V(2) pentenary semiconductors.  This work is not part of my current research. Click on the link to download pdf version.  Papers her are listed in order of publication

Refereed Journal Papers

J.J. Loferski, G.H. Chapman, J. Shewchun, S.D. Mittleman, E.A. De Meo, R. Arnott, H. L. Hwang, and R. Beaulieu, "Cathodoluminescence Characteristics of Cu(x)S Films Produced By Different Methods", Solar Energy Materials, 1, 1, 157- (1979). sem79CdS.pdf  762KB
This paper shows how the cathodoluminescence (CL) spectrum of chalcocite (Cu(2.00)S)  films like those in Cu-Cd-S solar cells can be used to develop information about the opto–electronic properties of the material. Comparison of the CL spectra of bulk polycrystalline samples known to be chalcocite with those of thin films produced by sulfurizing thin films of copper and of thin films produced by the chemical substitution processes commonly used to fabricate Cu – Cd-S cells, leads to the conclusion that the CL spectra of the latter may be affected by the presence of Cd as a dopant. This hypothesis was tested by observing the CL spectra of chalcocite samples which were doped with various amounts of cadmium. Comparison of these CL spectra suggest that chalcocite films derived from CdS contain 0.25 and 1.0 wt% Cd. The CL spectra of chalcocite films produced by dipping CdS crystals into aqueous solutions of cuprous chloride exhibit an ”ageing” process whose cause has not been identified. Cathodoluminescence was also observed from thin film and sintered samples containing a tetragonal phase (not djurleite) having an approximate composition Cu(1.96)S.

G.H. Chapman, J.J. Loferski, J. Shewchun, R. Beaulieu, and B.K. Garside, "Cu(1-y) Ag(y) In S(2(1-x)) Se(2x) as a Prototype of the Pentenary Chalcopyrite Semiconductor System for Solar Photovoltaic Cells", Solar Energy Materials, 1, 2, 451-469 (1979). sem79.pdf  1353KB
Group III–V mixed alloy quarternary semiconductors, such as Ga(1-y)In(y)As(1-x)P(x), have been extensively employed in lattice matching different semiconductor layers (at specified bandgaps) to form heterojunction electro–optical devices. The feasibility of employing the analogous pentenary alloys, consisting of the ternary chalcopyrites groups I–III–VI(2), and II–IV–V(2), are being reported. As a prototype of such alloys, samples of the pentenary Cu(1-y)Ag(y)InS(2(1-x))Se(2x), have been synthesized and studied. These were prepared by reacting stoichiometric powder mixtures at about 900C. X-ray diffractometry tests suggest the compounds maintain complete solid solubility throughout the system in a chalcopyrite type crystal structure, The alloy’s intrinsic conductivity type appears to tend towards n-type for silver and sulfer rich compounds, while forming p-type for copper and selenium rich materials. Using cathodoluminescence spectra the sample’s bandgap energies were estimated at 300 and 77 K. These indicate that all the alloys synthesized were direct bandgap semiconductors. Using least square fits on the data, topological maps of the bandgap and lattice constants versus composition have been produced.

J. Shewchun, G.H. Chapman, J.J. Loferski, R. Beaulieu, and B.K. Garside, "The A1(1-y) B1y C3 D6(2x) E62(1-x) Pentenary Alloy Systems and Its Application to Photovoltaic Solar Energy Conversion", Jour. Appl. Phys., 50, 6978 (1979). jap79.pdf  910KB
This paper reports work on pentenary alloy systems similar to the quarternary system in
In(1-x)Ga(x)P(1-y)As(y). Such A<I>(1-y)B<I>(y)C<III>D<VI>(2x)E<VI>(2(1-x)) and
A<II>(1-y)B<II>(y)C<IV>D<V>(2x)E<V>(2(1-x)) pentenary alloys are mixtures of ternary chalcopyrites of the I-III-VI(2) and II-IV-V(2) variety. These materials are of interest because their use can improve the performance of heterojunction electr-optic devices such as solar cells. This improvement arises because the pentenaries can permit different semiconductor layers to be deposited upon each other such that they are lattice and crystallographically matched, but at the same time have independently adjustable bandgaps. More specifically, we have focused on the Cu(1-y)Ag(y)InS(2(1-x))Se(2x) system which appears to have the best potential of all the possible systems for solar energy applications. Samples were prepared by reacting stoichiometric powder mixtures at about 900C. X-ray diffractometry indicated complete solid solubility over the whole compositional range. Cathodoluminescence was used to determine band gaps at 300 and 77K and the spectra indicate that all alloys are direct-band- gap semiconductors. Isolattice constant and band-gap contour maps for the system have been obtained.

G.H. Chapman, J. Shewchun, J.J. Loferski, B.K. Garside, and R. Beaulieu, "Lattice Constants and Band-Gap Variations of the Pentenary Semiconductor Systems Cu(1-y) Ag(y) In S(2(1-x)) Se(2x)", Applied Phys. Lett., 34, 11, 735- 737 (1979). apl79.pdf 302KB
Much interest has been expressed in the ternary I<B>-III-VI(2), group semiconductors for use in electro-optical devices such as solar cells. Subsets of these, AgInS(2),AgInSe(2),CuInS(2) and CuInSe(2) have been combined to form the pentenary alloy system Cu(1-y)Ag(y)InS(2(1-x))Se(2x). With such an alloy the band gap may be varied while keeping the lattice constant fixed. Samples were prepared by reacting stoichiometric powder mixtures at about 900C. X-ray diffractometry tests suggest the alloys maintained complete solid solubility throughout the system in a chalcopyrite- type crystal structure. From cathodoluminescence studies on pressed bars of these powders the band-gap energies were estimated at 300K. These tests suggest that the alloys are all direct- band-gap semiconductors.

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