Crystalline Organic Semiconductors: A New Class of Materials for Photonic Devices

Abstract

Today’s electronic and photonic devices are mainly based on inorganic materials. In the field of optoelectronic devices III–V compound semiconductors are predominant because of the direct band structure of these alloys. However, organic compounds may emerge to a remarkable enrichment. In the near future they will support or partly replace inorganic materials. Especially polymers and cristalline organic semiconductors are promising candidates for application in photonic devices. The experimental characterization of two well established aromatic compounds, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), and optoelectronic device fabrication are subjects of this contribution. We first discuss the deposition of crystalline organic layers by UHV sublimation. Optimized growth conditions even facilitate the growth of homogeneous quantum well structures. In view of applications in optoelectronic devices ohmic and Schottky contacts and organic-inorganic heterostructures are investigated. A planar photodetector is presented as a first example.