Massachusetts Institute of Technology

Frank W Smith

Arthur R Calawa

Mark Alexander Hollis

Han Q Le

Chang-Lee Chen

Vicky Diadiuk

Michael J Manfra

Elliott R Brown

Leonard J Mahoney

An apparatus and method for optical heterodyne conversion and a radiation source and integrated diagnostics using the apparatus and method are disclosed. The radiation source can operate in a high-power narrow-band mode in which a constant-frequency output is provided or in a low-power broadband mode in which the frequency is tunable to allow the radiation source to act as a sweep oscillator. The apparatus or photomixer includes two sets of interdigitated conductive electrodes formed on top of a crystal lattice formed of column III-V compounds, particularly InAlGaAs compounds. Additional column V atoms are interspersed within the lattice structure to form defect energy states in the bandgap of the host material. The region of the material between the interdigitated electrodes is illuminated by optical radiation containing two different frequencies. Photon absorption in the material causes a current at the difference frequency to be generated and coupled to the interdigitated electrodes. The current is then coupled to a planar transmission line or antenna structure to generate coherent, continuous-wave, unimodal radiation in the microwave, millimeter-wave, or submillimeter-wave regions.

Apparatus and method for optical heterodyne conversion

A new III-V buffer or passivation material is described which is produced by low temperature growth (LTG) of III-V compounds. The material has unique and desirable properties, particularly for closely spaced, submicron gate length active III-V semiconductor FET devices, such as HEMT's, MESFET's and MISFET's. The LTG material is grown under ambient conditions which incorporate an excess of the more volatile of the III-V species into the grown material. The new material is crystalline, highly resistive, relatively insensitive to light, and can be overgrown with high quality III-V active layers or used as a passivation material to insulate and protect active device structures.

III-V based integrated circuits having low temperature growth buffer or

An ultra-high-speed photoconductive device is described which comprises a homoepitaxial semi-insulating III-V layer, or body, upon which ohmic/conductive contacts, or strips, separated by a small gap, are formed. The semi-insulating body, or layer, is produced by low temperature growth of III-V compounds by MBE. In a GaAs embodiment, the layer is grown under arsenic stable growth conditions, at a substrate temperature preferably in the range of 150.degree. to about 300.degree. C.

Ultra-high-speed photoconductive devices using semi-insulating layers

A new III-IV buffer material is described which is produced by low temperature growth of III-V compounds by MBE that has unique and desirable properties, particularly for closely spaced, submicron gate length active III-V semiconductor devices, such as HEMT's, MESFET's and MISFET's. In the case of the III-V material, GaAs, the buffer is grown under arsenic stable growth conditions, at a growth rate of 1 micron/hour, and at a substrate temperature preferably in the range of 150 to about 300.degree. C. The new material is crystalline, highly resistive, optically inactive, and can be overgrown with high quality III-V active layers.

Growing community of inventors

Cambridge, MA, United States of America

Frank W Smith