The transmittance of InAsSb/InAsPSb heterostructures is remarkably improved by depositing a Si3N4 top layer. This demonstrates its good anti-reflective property. A study of the influence of various factors on the transmittance of the heterostructures is performed. A comparison was made between the transmittances of the heterostructures under different conditions. The different effects Of Si3N4 and ZnS top layers on the transmittance of the InAsSb/InAsPSb heterostructures are discussed. (c) 2004 Published by Elsevier B.V.