Electrical properties of Schottky contacts to N-type ZnS0.07Se0.93 epilayers

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Abstract
Schottky contacts were formed on Cl‐doped N‐type lattice matching ZnS0.07Se0.93 epilayers grown on (100) N‐GaAs substrates by molecular beam epitaxy for metals with different work functions, Yb, Al, Cr, Cu, Au, and Pd. Temperature‐dependent current‐voltage and capacitance‐voltage (C‐V) measurements show a clear relation between Schottky barrier height and metal work function which cannot be predicted by the linear Schottky contact theory, ΦSB=ΦM−χ. The pinning effect is believed to exist at the metal‐semiconductor interface with a wide range of Fermi level pinning positions. Thermionic emission dominates the current transport mechanism and the current is limited by the ZnSSe/GaAs heterojunction under a relatively high positive bias. A symmetriclike C‐V characteristic is explained by the Schottky barrier‐heterojunction model and a fairly constant heterojunction barrier height, ΦHJ, is obtained for Schottky diodes using different metals.