Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Patent
1994-11-18
1997-03-04
Crane, Sara W.
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
257 21, 257184, 257190, H01L 2906, H01L 310328, H01L 310336
Patent
active
056082304
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved strained superlattice semiconductor photodetector having a side contact structure.
2. Prior Art
While PIN type semiconductor photodetectors having pn junctions have been used in practical applications, Metal-Semiconductor-Metal (MSM) type semiconductor photodetectors realized by utilizing Schottky junctions have been attracting researchers' attention.
Since an MSM type semiconductor photodetector comprising a pair of oppositely disposed electrodes on a crystal surface is particularly suited for use in a highly integrated circuit such as an OEIC (opto-electronic integrated circuit), a number of studies have been made in this technological field.
While an MSM type semiconductor photodetector has advantages of having a very small capacity and being structurally simple and therefore capable of being produced with a reduced number of manufacturing steps, it has certain technological problems to be solved before it can make a feasible opto-electronic device, including a relatively large dark current that has to be reduced and a relatively long rise time of the responding pulse that needs to be curtailed in order to achieve a fast pulse response.
A long rise time of the responding pulse of an MSM type semiconductor photodetector is attributable to the fact that holes generated as a result of optical absorption move rather slowly so that they tend to get to the cathode considerably long after the end of light exposure.
The use of a strained superlattice has been proposed as means for accelerating holes in order to eliminate the above identified technological problems.
This proposal is based on the fact that, if a semiconductor photodetector has a strained superlattice structure, the effective mass of holes in the strained superlattice layer having intra-planar compressive strains of the device is reduced along intra-planar directions to enhance the mobility of holes, when compared with a device having no strained structure.
FIG. 4 illustrates a typical MSM type semiconductor photodetector realized by utilizing a strained superlattice structure.
Referring to FIG. 4, a nondoped InP buffer layer 12, a photodetective layer 13 having a strained superlattice structure and comprising an InGaAs compressive strain layer and an InGaAs tensile strain layer, a non-doped InAlAs layer and Ti/Pt/Au electrodes are sequentially laid on a (100) Fe-doped InP substrate 11.
An MSM type semiconductor photodetector having a strained superlattice structure as shown in FIG. 4 is accompanied by the following problems when it is used for a practical application. superlattice structure, carriers move perpendicularly relative to the strained superlattice until they get to an electrode.
In other words, their responsiveness is degraded as they pass over a barrier layer of the strained superlattice (and they give rise to a pile up phenomenon at a heterobarrier). tensile strained superlattice layers and caused to move toward an electrode in the two strained superlattice layers. While holes behave as lightweight holes in the compressive strained superlattice layer, they remain as heavyweight holes in the tensile strained superlattice layer so that the speed at which they move cannot be significantly improved as a whole. junctions to increase the dark current of the device because of a low Schottky barrier between each electrode and a semiconductor on the InP substrate of the device.
SUMMARY OF THE INVENTION
In view of the above identified technological problems, it is therefore an object of the present invention to provide an MSM type semiconductor photodetector having a strained superlattice structure that shows a high responsiveness and, at the same time, a reduced dark current.
According to the invention, the above object is achieved by providing a strained superlattice semiconductor photodetector comprising semiconductor layers including a photodetective layer having an intra-planar compressive strain type strained superlattice layer formed on a sem
REFERENCES:
patent: 5132981 (1992-07-01), Uomi et al.
patent: 5155738 (1992-10-01), Ijichi et al.
patent: 5238869 (1993-08-01), Shichijo et al.
Fritz et al., "Novel relectance modulator employing an InGaAs/AlGaAs strained-layer superlattice Fabry-Perot cavity with unstrained InGaAs/InAlAs mirrors," Appl. Phys. Lett., vol. 58, No. 15, 15 Apr. 1991, pp. 1608-1610.
Hirayama Yoshiyuki
Irikawa Michinori
Nishikata Kazuaki
Crane Sara W.
The Furukawa Electric Co. Ltd.
LandOfFree
Strained superlattice semiconductor photodetector having a side does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Strained superlattice semiconductor photodetector having a side , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Strained superlattice semiconductor photodetector having a side will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2147956