University of Southern California

Franky F So

Stephen R Forrest

De Yu Zang

Organic optoelectronic devices, such as a modulator (54) and a photodetector (73) comprising alternating layers (58) of two crystalline planar organic aromatic semiconductors (60 and 62), have been grown by organic molecular beam deposition. These organic substances have been deposited in ultra-thin layers only 10 .ANG. in depth using organic molecular beam deposition methods. Due to the anisotropic character of these organic materials,, the devices formed using these methods possess unique electronic and optical properties. The preferred embodiment of the invention utilizes 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and 3,4,7,8-naphthalenetetracarboxylic dianhydride (NTCDA). While the inventors have identified PTCDA and NTCDA as excellent materials for the manufacture of organic optoelectronic IC devices, the broad scope of the present invention encompasses the use of any planar organic aromatic semiconductor which readily forms a crystalline structure. The preferred method of the invention employs a chamber (23) containing an inorganic substrate (32) with appropriate material for making electrical contact to the organic structures and sources of PTCDA (36) and NTCDA (38). The chamber (23) is maintained at a pressure which is generally less than 10.sup. -6 Torr. The substrate (32) is separated from the source materials by a minimum separation distance of 10 cm. The substrate (32) is held below 150K while the PTCDA and NTCDA are alternately heated. The methods described above may also be employed to fabricate an organic phototransistor/photodetector (78).

Organic optoelectronic devices and methods

Certain crystalline organic semiconductor compounds, such as 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), when deposited by an ultrahigh vacuum process of organic molecular beam deposition, form highly ordered 'quasi-epitaxial' films (32). Due to asymmetries in the molecular crystal structure of such compounds, the ordering of the films results in giant asymmetries in their dielectric properties. Such large dielectric asymmetries permit the construction of a variety of devices, including optical isolators (38), optically isolated lasers (48), optical isolated optical amplifiers (64), polarization-selective photodiodes (76), and metal-organic-inorganic semiconductor-metal detectors, among others.

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Torrance, CA, United States of America

Franky F So