Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal
Reexamination Certificate
1998-12-24
2001-05-08
Lee, Eddie C. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
C257S080000, C257S081000, C257S083000, C257S084000, C257S431000, C438S022000, C438S024000
Reexamination Certificate
active
06229189
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a multi-function semi-conductor device. More specifically, the present invention relates to a monolithic device having both an optoelectronic (OE) and an electronic device sharing certain layers.
BACKGROUND ART
Circuits that combine optoelectronic (OE) and electronic devices have applications in communication (e.g. as transmitters and receivers for optical fiber based links or for free-space interconnections). Such circuits also are used to form optoelectronic switched networks in applications such as photonic beam forming for phased-array antennas. Switched networks are also used for multi-sensor and multi-processor systems, multi-channel radar imaging, high speed data routing, and digital beam forming.
Commonly, circuits that combine OE and electronic devices are formed of a number of separate components manufactured separately and combined in a hybrid-packaged assembly. Such assemblies have the deficiencies of degraded performance due to packaging parasites. In addition, there is additional cost that results from the hybrid assembly procedures. Monolithic circuits, in which the OE and electronic devices are formed on a common substrate, have been developed as an alternate to the hybrid packaging and assemblies.
One known monolithic optoelectronic receiver is based on a standard, single-heterojunction bipolar transistor (HBT). In this approach, the collector of the standard HBT also serves as the light-absorbing layer of the photodetector. The base, collector and subcollector layers are all fabricated from the smallest bandgap material of the overall structure. This results in these layers being optically absorbing. In the known example, InGaAs is used. One problem with this approach is that only receivers and not transmitters, modulators or optoelectronic switches may be fabricated. This is due to the unattenable characteristics of the optically absorbing layers.
Other known devices have optoelectronic modulators and detectors that have been pseudo-monolithically integrated with transistors. These devices are heterostructure field effect transistors. The modulator and photodetector of such devices have multiple-quantum well structures. The only epitaxial layer that the electronic and optoelectronic devices have in common is the top layer and, thus, are only minimally monolithically integrated. One problem with such devices is that the devices have low current driving capabilities. Another drawback of such devices is that high-resolution photolithography is used to form the gate structure. High resolution photolithography is an expensive process.
Another known heterojunction phototransistor uses a light absorbing layer that is part of the collector. The light absorbing layer has a smaller bandgap than the emitter, base and subcollector layers. The light absorbing layer is intentionally kept thin so as not to degrade the performance of the transistor. One problem with such device is that because the light absorbing layer is so thin, a multi-layer reflector underneath the subcollector is needed to create a resonant optical cavity to enhance the photo sensitivity.
SUMMARY OF THE INVENTION
It is a general object of the invention to fabricate a monolithic epitaxial layered optoelectronic and electronic device that share the same epitaxial layers.
In one aspect of the invention, epitaxial layer structure has a substrate and a first layer formed adjacent to the substrate. The first layer may, for example, form a contact layer. A second layer is formed adjacent to the first layer. The second layer forms a selectively optically varying layer, so that during a first state the second layer is optically absorbing and during a second state the layer is optically transparent. A third layer is formed adjacent to the second layer. A fourth layer is formed adjacent to the third layer. The fourth layer is an optically transparent layer. An optoelectronic device and an electronic device may be formed on the same substrate that share the same layers.
One advantage of the invention is that the simpler fabrication procedure results in higher fabrication yield lowering ultimate cost. A further advantage of the invention is that by forming the subcollector layer to be optically non-absorbing, the optoelectronic device may be an optoelectronic modulator or optical waveguide coupled device.
The present invention thus makes possible compact optoelectronic circuits and switch networks. Since both the photoreceiver and transmitter may be fabricated on the same chip.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 5260586 (1993-11-01), Kondo et al.
patent: 5376185 (1994-12-01), Wanlass
patent: 5764826 (1998-06-01), Kuhara et al.
patent: 5811838 (1998-09-01), Inomoto
Docter Daniel
Stanchina William
Yap Daniel
Gudmestad T.
Hughes Electronics Corporation
Lee Eddie C.
Warren Matthew E.
LandOfFree
Multi-function optoelectronic device structure does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-function optoelectronic device structure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-function optoelectronic device structure will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503801