JPH02199877A - Optical receiver and photoelectric integrated circuit - Google Patents

Abstract

PURPOSE:To enhance the performance of an optical receiver, to enhance the performance of a photoelectric integrated circuit integrated therewith, to highly integrate it and to enhance reliability by forming a light absorption layer having a multiple quantum well structure in the optical receiver, and composing the multiple quantum well(MQW) structure of a low carrier concentration layer. CONSTITUTION:In order to integrate an optical receiver in a photoelectron integrated circuit, a GaAs buffer layer 21 is laminated on a semi-insulating InP substrate 1. Then, a GaAs channel layer 22 is laminated thereon. The optical receiver section is removed up to an InP board by mesa etching. Then, a nondoped InP layer 2, a nondoped InGaAs/InP MQW light absorption layer 3, and a nondoped InP layer 4 are sequentially grown on the InP board l. Further, a nondoped InAIAs layer 15 is grown. Thereafter, after the layer 15 of the center of the photodetecting face is mesa etched, a Ti/Pt/Au Schottky electrode is formed on the remaining InAlAs layer to form the optical receiver. Further, Ti/Pt/Au is deposited on the gate electrode of a field effect transistor, AuGe/Ni/Au is deposited on source, drain electrodes, wirings are eventually formed to form a photoelectric integrated circuit.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to optical receivers and optoelectronic integrated circuits.

[Conventional technology]

With the progress of optical communication technology, its application fields are rapidly expanding from core transmission systems to systems such as subscriber systems, LANs, and data rings. In order to respond to such advances in optical systems, it is essential that optical devices have higher performance, higher functionality, and higher integration.

Optical receivers are one of the key devices in these optical systems. In addition, optoelectronic integrated circuits integrate optical receivers, optical transmitters, and electronic circuits that drive or amplify them on the same chip, and have the basic advantages of integration such as low cost, small size, high reliability, and no adjustment. In addition, the aim is to improve the performance of optical devices, such as faster speeds and higher sensitivity, and to realize devices with new functions.

Conventionally, as a constituent material of an optical receiver, 0. In the δμm band, G
aAs-based material or Si in lj μm band or 1.55 μm
InP-based material is used in the band. For example, 1.3μ
In the m band, a pin structure is formed by InP/IoGaAs/InP and Zn diffusion to form an optical receiver. A physical quantity that measures the performance of an optical receiver is quantum efficiency η, and the larger η is, the higher the reception sensitivity is. Generally, in an optical receiver using a pn junction, η is the surface reflectance, R5 is the absorption coefficient of the light absorption layer is a, the depletion layer width is w, and the n-side depletion layer width is X, then 77= (1- R)e-aX(1
−e−”) −(1). Therefore, in order to increase η, methods such as decreasing R, that is, coating the light-receiving surface with anti-reflection coating, are used. Also, the depletion layer width W is However, in order to increase the depletion layer width W, the absorption layer thickness d must be increased, and if d is made too large, the response speed will be limited by the carrier transit time, making it difficult to operate at high speed. In addition, when an optical receiver with a large absorption layer thickness d is used in an optoelectronic integrated circuit, there are problems such as a large step difference on the substrate surface and the inability to miniaturize electronic elements. arise.

[Problems to be Solved by the Invention] It is an object of the present invention to compensate for the contradictory aspects of increasing the sensitivity and speed of an optical receiver, to improve the performance of the optical receiver, and to further improve the performance of the optical receiver, and furthermore, to Higher performance and higher integration of integrated circuits,
The aim is to achieve high reliability.

[Means to solve the problem]

In order to solve the above problems and achieve the above objects, the present invention provides an optical receiver including a light absorption layer having a multiple quantum well structure, wherein the multiple quantum well (MQW) structure has a low carrier concentration. The multi-quantum well structure includes means for applying a parallel electric field to each layer of the multi-quantum well structure, and the multi-quantum well is depleted by the electric field generated by the electric field applying means. In addition, optoelectronic integrated circuits are manufactured using a G-containing layer containing AlG1As formed on a semi-insulating InP substrate with a strained buffer layer made of GaAs or ^lGaAs.
aAs-based semiconductor electronic device or the semi-insulating In
an InP-based semiconductor electronic device lattice-matched to a P substrate;
The structure is characterized in that the above-mentioned optical receiver is integrated.

[Effect]

It is known that the MQW structure has an absorption peak due to exciton resonance at room temperature. The absorption coefficient a at this absorption peak is larger than that of the bulk crystal. When an electric field perpendicular to the stacking direction is applied to this MQW structure, the exciton absorption peak disappears without changing the peak wavelength due to exciton ionization (physical Levi x
-B (Physical Review B) 3rd
2, pp. 1043-1060 (1985)), the electric field strength for the absorption peak to disappear is approximately 1×10'V/C11, and the applied voltage is 10 V for a layer thickness of 1 μm.

Therefore, an exciton absorption peak with a large absorption coefficient exists at an electric field strength at which the light absorption layer of the MQW structure is depleted. According to formula <1), in order to increase η,
Since it is sufficient to increase the absorption coefficient a, a large η can be obtained with the same layer thickness by setting an exciton absorption peak where a is larger than the bulk at a desired wavelength. This makes it possible to improve the performance of optical receivers, and in optoelectronic integrated circuits that integrate optical receivers, it is possible to reduce the height difference on the substrate, making it possible to miniaturize electronic elements, resulting in higher performance and higher speeds. ,
Highly integrated devices are possible.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram for explaining the optical receiver of the present invention.

Figure 1 (a) shows the case where the electric field applied to the multiple quantum well is via a pn junction. Figure 1 (b) shows the case where the electric field applied to the multiple quantum well is via the Schottky electrode. Hereinafter, a method for manufacturing an optical receiver in the case shown in FIG. 1(a) will be described.
nP layer 2, non-doped IoGaAs/In? (30 people 1
50 people x 200) MQW light absorption layer 3, non-doped InP
Layer 4 is grown sequentially. Here, the composition of MQW is InGa
The reason for using As/InP (30 people and 150 people) is to set the exciton absorption peak wavelength to 1.3 μm. Next, perform selective diffusion of 2n using 5i02 as a mask, and p
Two type inversion layers are formed on the light receiving surface of the MQW light absorption layer.

Finally, opposing AuZn electrodes 6 are formed on top of the Zn diffusion region 5, and ^Ge/old HaU electrodes 7 are formed on the InP4.
By using ohmic electrodes, the optical receiver shown in FIG. 1(a) is completed. In the case of Figure 1(b), non-doped I
After growing nP 4, a non-doped InAlAs layer 1 is further grown.
InAlAsnAl at the center of the zero-order light-receiving surface growing 5
After 5 layers on the As layer, Ti/P is applied on the remaining 51 layers of InAlAl.
A t/Au short key electrode is formed, and the optical receiver shown in FIG. 1<b> is completed.

FIG. 2 is a diagram for explaining changes in the exciton absorption peak when an electric field (transverse electric field) is applied to the MQW perpendicular to the stacking direction. As the electric field intensity increases, the peak intensity (absorption coefficient a) decreases without changing the position of the exciton peak wavelength.

However, the magnitude of the absorption coefficient is smaller than that of bulk IaGa
According to equation (1), which is about 1.5 times larger than As, the quantum efficiency of the optical receiver can be expressed as an exponential function of a, so as a becomes larger, η becomes larger as a power of the inter-exponential number. Therefore, the optical reception sensitivity is also higher than in the past.

FIG. 3 is an example in which the optical receiver shown in FIG. 1(b) is integrated into an optoelectronic integrated circuit. Ga on semi-insulating InP substrate 1
A zero-order GaAs channel layer (layer thickness 0.3 μm) is formed by laminating an As buffer layer (layer thickness 1.5 μm) 21 by the MBE method.
) 22 are stacked. Using the silicon nitride film as a mask, the first receiver portion is removed down to the InP substrate by mesa etching.

Non-doped InP layer 2, non-doped InGaAs/In
A PM QW light absorption layer 13, a non-doped InP layer 4, and a non-doped InAlAs layer 15 are selectively grown by the MOVPE method. After processing the optical receiver part as shown in Fig. 1(b), Ti/Pt/Al was applied to the Schottky electrode of the optical receiver and the gate electrode of the field effect transistor, and ^Ge/was applied to the source and drain electrodes of the field effect transistor. Ni/Au is deposited and finally wiring is applied to complete the optoelectronic integrated circuit shown in FIG. When forming an electronic circuit at this time, since there were almost no steps on the substrate, a good electronic device with a gate length of 0.7 μm was formed. The embodiment shown in FIG. 3 operates as an opto-electronic integrated circuit for optical reception in which an optical receiver, electric field and effect transistors are monolithically integrated on a semi-insulating InP substrate.

In the above embodiment, the Schottky electrode of the optical receiver and the gate electrode of the field effect transistor are made of Ti/P.
It is not limited to t/Al, but any material that can form a Schottky junction may be used, and the thickness, carrier concentration, and composition of the active layer of the field effect transistor may be any material as long as it is optimized for an electronic device for optoelectronic integrated circuits. good,
Further, there may be a plurality of optical receivers, and they may be integrated with optical functional elements such as optical bistable elements and optical amplifiers through optical waveguides.Electronic devices include not only GaAs field effect transistors but also diodes, may include resistance,
The scale of the accumulation may also be larger.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to improve the reception sensitivity of an optical receiver, and by integrating the optical receiver into an optoelectronic integrated circuit, it is possible to miniaturize electronic devices, thereby achieving high performance and high reliability. An optoelectronic integrated circuit is obtained.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are diagrams showing embodiments of the optical receiver of the present invention, in which (a) is an example using a pn junction, and (b) is an example using a Schottky electrode. be. FIG. 2 is a diagram for explaining the present invention in detail. Further, FIG. 3 is a diagram for explaining an embodiment in which the optical receiver of the present invention is integrated into an optoelectronic integrated circuit. 3...MQW light absorption layer, 5...Zn diffusion region (p-type inversion region), 6,7.16...electrode. Agent: Patent Attorney Susumu Uchihara (2)

Claims (2)

[Claims] (1) A light absorption layer having a multiple quantum well structure, wherein the multiple quantum well (MQW) structure is composed of a low carrier concentration layer, and means for applying a parallel electric field to each layer of the multiple quantum well structure. an optical receiver, wherein the multiple quantum well is depleted by an electric field generated by the electric field applying means. (2) GaAs or AlGa on a semi-insulating InP substrate
AlG formed between strained buffer layers made of As
2. An optoelectronic integrated circuit comprising a GaAs-based semiconductor electronic device containing aAs or an InP-based semiconductor electronic device lattice-matched to the semi-insulating InP substrate and the optical receiver according to claim 1.