JPH0575186B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in optoelectronic integrated circuits.

(Prior art and its problems) With the progress of optical communication technology, its application fields are rapidly expanding from backbone transmission systems to systems such as subscriber systems, LANs, and data links. In order to respond to such advancements in optical systems, it is imperative that optical devices have higher performance and functionality.

Optoelectronic integrated circuits are one of the key devices at the core of these optical systems. In other words, not only are the basic benefits of integration such as low cost, small size, high reliability, and no adjustment required, but also improvements in the performance of optical devices such as faster speeds and higher sensitivity, as well as improvements in optical interconnection, optical switching, and more. The aim is to realize highly functional and new functional devices that will support future optical systems.

InP-based materials are excellent in terms of reliability of optical devices and compatibility with the low-loss and low-dispersion wavelength bands of optical fibers. In the field of optical communications, devices using this material have already been put into practical use and have a proven track record. There is.

Because InP-based semiconductors cannot obtain good shot contact, which is important in electronic devices, MSFETs (metal-insulator-semiconductor field effect transistors) are used instead of MESFETs (metal-semiconductor field effect transistors).
Research and development is progressing on FETs (FETs), JFETs (junction gate FETs), and HBTs (heterojunction bipolar transistors). However, MISFET has
There is a problem of large drift caused by the interface states, and although JFETs and HBTs are stable in operation, their structures and processes are complex, making it difficult to integrate them with optical devices. On the other hand, since GaAs-based semiconductors can form good shot-key contacts, advances in FET integration process technology based on MESFETs will soon bring LSI-class ICs to practical use. However, the reliability of the optical device is poor, and the transmission capacity is severely limited by the transmission loss and chromatic dispersion of the optical fiber.

By compensating for these contradictory drawbacks of InP-based materials and GaAs-based materials, InP-based materials and GaAs-based materials can be used as optical devices.
Studies are underway to realize the optimal combination of GaAs-based materials for electronic devices by optoelectronic integrated circuits using composite materials of GaAs-based and InP-based materials. (M.Razeghi, Appl.Phys.Lett,
vol.49, pp.215, 1986) This is a semi-insulating GaAs
GaInAs is grown on a substrate using strained heteroepitaxy using low-pressure MOVPE, and a photodetector made of GaInAs and a MESFET made of GaAs are monolithically integrated.

However, in this conventional example, optical devices, which are minority carrier devices, are semi-insulating.
Since it is grown on a GaAs substrate by strained heteroepitaxy, it is greatly affected by dislocations due to lattice misalignment, which not only makes it impossible to obtain sufficient device characteristics as an optical communication device, but also significantly reduces the device reliability of the optical device. It had the disadvantage of being low.

An object of the present invention is to eliminate these drawbacks and provide a high performance and highly reliable optoelectronic integrated circuit.

(Means for Solving the Problems) In order to solve the above problems and achieve the above objects, an optoelectronic integrated circuit provided by the present invention includes InGaAs or InGaAsP on a semi-insulating InP substrate.
An optical device made of an InP-based semiconductor and a field effect transistor made of a GaAs-based semiconductor including AlGaAs are monolithically integrated on the semi-insulating InP substrate with a strained buffer layer made of GaAs or AlGaAs sandwiched therebetween. It is characterized by

(Function) By constructing an InP-based semiconductor containing InGaAs or InGaAsP that is lattice-matched to InP on a semi-insulating InP substrate, a high-performance and highly reliable optical device can be obtained.

In addition, GaAs or AlGaAs is deposited on a semi-insulating InP substrate.
By constructing a field effect transistor made of GaAs-based semiconductors including AlGaAs with a strain buffer layer made of performance and reliability. Therefore, it is possible to realize an optimal combination of an InP-based material for an optical device and a GaAs-based material for an electronic device as an optoelectronic integrated circuit while ensuring the performance and reliability of the device.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of the optoelectronic integrated circuit of the first embodiment. As shown in the figure, this optoelectronic integrated circuit is made of n-type In _0.87 Ga _0.13 As _0.29 P _0.71 with a layer thickness of 1 μm and a carrier concentration of 1×10 ¹⁸ cm ^-3 on a semi-insulating InP substrate 1.
Laser contact layer 2 and oscillation wavelength of 1.3μ
mesa-type buried laser 3 made of InP and InGaAsP with a layer thickness of 0.5 μm, and an undoped n-type laser with a layer thickness of 0.5 μm.
A field effect transistor with a gate length of 1 μm includes a strained buffer layer 4 made of GaAs, an active layer 5 made of GaAs with a layer thickness of 0.2 μm and a carrier concentration of 1×10 ¹⁷ cm ⁻³ , and a gate electrode 6 of Al with a thickness of 0.3 μm. Consists of 7.
Note that the drain electrode 8, the source electrode 9, and the n of the laser
The electrode 10 is AuGeNi, and the p-electrode 11 of the laser is
AuZn and the wiring 12 are made of Ti/Au.

FIGS. 2-a to 2-c are manufacturing process diagrams of the optoelectronic integrated circuit of this embodiment. First, a laser contact layer 2 and a buried laser layer 13 are formed by liquid phase epitaxy or vapor phase epitaxy on a semi-insulating InP substrate 1 having a step difference of about 5 μm (FIG. 2-a). Next, the laser layer 13 is formed into a mesa stripe, the laser contact layer 2 is mesa-etched, the semi-insulating InP substrate 1 is exposed, and a mask 15 made of SiO ₂ is applied to the laser mesa portion 14, followed by molecular beam epitaxy or MOVPE.
A strain buffer layer 4 and an active layer 5 are formed by the method (FIG. 2-b). Next, the active layer 5 and strain buffer layer 4 on the mask 15 are removed, and the active layer of the field effect transistor 7 is formed by mesa etching (second
Figure-c). Next, each electrode and wiring are formed, and the optoelectronic integrated circuit of this example is completed (FIG. 1).

The first embodiment operates as an optoelectronic integrated circuit for optical transmission in which a mesa-type buried laser 3 and a field effect transistor 7 are monolithically integrated on a semi-insulating InP substrate 1.

FIG. 3 is a sectional view of the optoelectronic integrated circuit of the second embodiment. This optoelectronic integrated circuit is formed on a semi-insulating InP substrate 1 with a layer thickness of 1 μm and a carrier concentration of 1×10 ¹⁸ cm.
^-3 n-type In _0.87 Ga _0.13 As _0.29 P _0.71 photodiode contact layer 17 sandwiching the bandgap energy wavelength of 1.67 μm In _{0.47 Ga 0.53 As light absorption layer 19 made of In 0.47} Ga _0.53 As PIN photodiode 1
6, and an undoped n-type layer with a layer thickness of 0.5 μm.
A strain buffer layer 4 made of GaAs is sandwiched between the active layer 5 made of GaAs with a layer thickness of 0.2 μm and a carrier concentration of 1×10 ¹⁷ , and a gate electrode 6 made of Al with a thickness of 0.3 μm.
The field effect transistor 7 has a gate length of 1 μm.

The manufacturing process of this embodiment is similar to that of the first embodiment.
First, n-type In _0.87 was deposited on a semi-insulating InP substrate 1 with a step height of about 3 μm by liquid phase growth or vapor phase growth.
Photo diode consisting of Ga _0.13 As _0.29 P _0.71
Contact layer 17 (thickness 1.0 μm, carrier concentration 1×10 ¹⁸ cm ⁻³ ), photo diode buffer layer 18 made of n-type InP (thickness 0.5 μm, carrier concentration 2×10 ¹⁵ cm ⁻³ ), Light absorption layer 19 made of n-type In _0.47 Ga _0.53 As (thickness 1.0 μm, carrier concentration 2×
10 ¹⁵ cm ^-3 ), window layer 20 made of n-type InP
(thickness: 1.0 μm, carrier concentration: 2×10 ¹⁵ cm ^-3 ) are sequentially formed. Next, leaving the PIN photodiode portion 16, the photodiode contact layer 17, photodiode buffer layer 18, light absorption layer 19, and window layer 20 are mesa-etched to expose the semi-insulating InP substrate 1. To the PIN photodiode section 16
A strain buffer layer ₄ made of GaAs (thickness 0.5 μm, non-doped) and an active layer 5 made of n-type GaAs (thickness 0.2 μm, carrier concentration 1 ×10 ¹⁷
cm ^-3 ). Next, the active layer 4 and buffer layer 4 on the PIN photodiode section 16 are removed, and then the active layer of the field effect transistor 7 is formed by mesa etching. Next, zinc is selectively diffused using a mask made of SiO ₂ to form a p-type inversion region 21, and a gate electrode 6, a drain electrode 8, a source electrode 9, an n-electrode 10, a p-electrode 11, and a wiring 12 are formed. The optoelectronic integrated circuit of the second embodiment is completed.

The second embodiment operates as an opto-electronic integrated circuit for receiving light, in which a PIN photodiode 16 and a field effect transistor 7 are monolithically integrated on a semi-insulating InP substrate 1.

In the above-mentioned embodiment, the gate electrode of the field effect transistor is not limited to Al, but any material that can form a Schottky junction may be used, and the thickness, carrier concentration, and composition of the active layer are optimal for use as an electronic device for optoelectronic integrated circuits. It may be of any structure as long as it has a heterostructure containing an AlGaAs mixed crystal, and may also be a structure that utilizes a two-dimensional electron gas having a heterostructure containing an AlGaAs mixed crystal. Further, the optical device may be a light emitting diode, an avalanche photo diode, or an optical functional element such as an optical bistable element, an optical amplifier, or an optical switch. The electronic circuit may also include not only GaAs field effect transistors but also diodes and resistors, and the scale of the integrated circuit may be even larger.

(Effects of the Invention) As explained above, according to the present invention, an optical device is formed on a semi-insulating InP substrate with lattice matching.
A field-effect transistor made of InGaAsP or an InP-based semiconductor containing InGaAs, and a field-effect transistor made of a GaAs-based semiconductor containing AlGaAs sandwiched between a strained buffer layer made of a GaAs-based semiconductor on a semiconducting InP substrate provides high performance. In addition, a highly reliable optoelectronic integrated circuit can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram of an optoelectronic integrated circuit according to a first embodiment of the present invention, and FIGS. 2 a to 2 c are diagrams of its manufacturing process. FIG. 3 is a cross-sectional structural diagram of an optoelectronic integrated circuit according to a second embodiment of the present invention. In the figure, 1 is a semi-insulating InP substrate, 2 is a laser contact layer, 3 is a mesa-type buried laser, 4 is a strain buffer layer, 5 is an active layer, 6 is a gate electrode, 7 is a field effect transistor, and 8 is a drain Electrode, 9 is a source electrode, 10 is an n electrode, 11 is a p electrode, 12 is a wiring, 13 is a laser layer, 14 is a laser mesa portion, 15 is a mask, 16
is a PIN photodiode, 17 is a photodiode contact layer, 18 is a photodiode buffer layer, 19 is a light absorption layer, 20 is a window layer, and 21 is a p-type inversion region.

Claims (1)

[Claims] 1 InGaAs or
An optical device made of an InP-based semiconductor containing InGaAsP, and a GaAs or
With a strained buffer layer made of AlGaAs in between,
An optoelectronic integrated circuit characterized by monolithically integrating field effect transistors made of GaAs-based semiconductors including AlGaAs.