KR0170191B1 - Non-biased optical bistable device - Google Patents

Abstract

The present invention relates to an optical bistable logic device, and in particular, a first process of growing a compound semiconductor multilayer mirror layer on a semi-insulating semiconductor substrate; A second process of forming a first conductive layer on the lower mirror layer formed in the first process; A third process of forming an optically active intermediate layer multiple quantum well layer on the first conductive layer formed in the second process; A fourth process of forming a second conductive layer on the layer formed in the third process by using a doping material having a polarity different from that of the doping material used for forming the first conductive layer; A fifth process of forming an optically active intermediate layer multiple quantum well layer on the second conductive layer formed in the fourth process; A sixth step of forming a first conductive layer of the second step on the well layer; A seventh process of sequentially forming the upper mirror layer at a predetermined thickness L from the lower mirror layer of the first process by sequentially repeating the third and fourth processes (or fifth and sixth processes); A method of manufacturing a voltage-free optical bistable device, and a vertical structured optical modulator combined with a resonance structure and a stacked diode structure, which is driven by itself without an external power source to operate by its own diode bias without an external voltage. It provides the structure of the voltageless photo bistable logic device, which uses its own bias, and combines the asymmetric resonance structure with the stacked structure to reduce the thickness of the intermediate layer of each stacked diode to obtain a sufficiently large driving electric field even by its own bias. It has the effect of making it possible.

Description

NON-BIASED OPTICAL BISTABLE DEVICE

1 is an example of a structure composed of an asymmetric resonator and a stacked diode according to the present invention (P-I-N-I-P ...).

2 is a cross-sectional view of a voltageless optical logic device having an asymmetric resonance structure and a stacked diode structure according to the present invention.

3 is a plan view of an implementation of the voltage-free optical bistable element shown in FIG.

* Explanation of symbols for main parts of the drawings

1: semi-insulating semiconductor substrate

2: high reflectivity mirror layer, undoped / 4n _H layer and undoped Laminated semiconductor mirror layer of / 4n _L layer (n _H ; refractive index of high refractive index layer, n _L ; refractive index of low refractive index layer)

3, 7: P ⁺ semiconductor electrode layer heavily doped (or N ⁺ electrode layer heavily doped)

4,6: optically active layer of undoped semiconductor multi-quantum well layer and buffer layer

5: highly doped N ⁺ semiconductor electrode layer (or heavily doped P ⁺ electrode layer)

8: A mirror layer film having a structure of the semiconductor / air plane mirror layer or the high reflectivity mirror layer 2 and having a lower reflectance than the mirror layer 2.

L: the operating wavelength of the optically active layers 4 and 6 at a thickness between the 2 and 8 mirror layers ) Has an optical distance of half the integer (m) times. That is, L = m (2n _avg ), where n _avg is the average refractive index in the resonator.

9: insulating film (e.g., SiNx) 10: P-omic metal

11: N-omic metal 12: Metal wiring connecting ohmic metal

31 first mesa structure 32 second mesa structure

33: isolation structure

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical bistable logic devices, and more particularly, to a voltageless optical bistable logic device for operating an entire voltageless voltage structure using a resonance structure on a semiconductor substrate and a stacked diode.

Since a conventional optical device applies a voltage from the outside, there are physical limitations of the device such as a high switching energy to use as a light exchange device for a large-capacity ultrafast optical information signal.

In addition to the above-described prior art, the device of the conventional resonant structure PIN structure has a predetermined thickness 1 between P and N in order to obtain a high optical signal contrast ratio. However, this thickness (1) was thicker than the diode's own bias (Vb), and thus, a sufficient driving electric field could not be obtained, thereby requiring an external voltage (Va). That is, the PIN structure of the prior art has an electric field of (Va + Vb) / 1.

An object of the present invention to solve the above limitations is to use its own bias, and by combining the resonance structure to the stacked structure, reducing the thickness of the intermediate layer of each stacked diode to generate a driving field large enough by its own bias. It is to provide a voltage-free optical bistable logic device to obtain.

A feature of the present invention for achieving the above object is that the vertical structure modulator combined with the resonance structure and the stacked diode structure is driven by itself without an external power source to operate by its diode bias without an external voltage applied.

Another feature of the present invention for achieving the above object is that the pin diode structure is repeatedly determined after determining the number of cycles of the quantum well so that the intermediate active layer in the pin diode structure can be sufficiently operated by the intrinsic potential of the semiconductor PN junction. By stacking in the vertical direction, it has a large light sensitivity in the resonance structure.

An additional feature according to the features of the present invention for achieving the above object is a single diode resonant structure is a structure that satisfies the resonance conditions, it is difficult to sufficiently modulate the light at a given intrinsic potential, by distributing it to the multilayer diode and using a resonator at the same time It has a very large signal contrast ratio and an extremely large optical signal difference in voltage.

Another feature of the present invention for achieving the above object is a first process for growing a compound semiconductor multilayer mirror layer on a semi-insulated semiconductor substrate; A second process of forming a first conductive layer on the lower mirror layer formed in the first process; A third process of forming an optically active intermediate layer multiple quantum well layer on the first conductive layer formed in the second process; A fourth process of forming a second conductive layer on the layer formed in the third process by using a doping material having a polarity different from that of the doping material used for forming the first conductive layer; A fifth process of forming an optically active intermediate layer multiple quantum well layer on the second conductive layer formed in the fourth process; A sixth step of forming a first conductive layer of the second step on the well layer; A seventh process of sequentially forming the upper mirror layer at a predetermined thickness L from the lower mirror layer of the first process by sequentially repeating the third and fourth processes (or fifth and sixth processes); Characterized in that made. The polarity of the first conductive layer P and the second conductive layer N may be changed.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

In general, an asymmetric resonance-layered diode structure on a semiconductor substrate operates a semiconductor of an Al _x Ga _1-x As layer and an AlAs layer on a semi-insulated GaAs substrate 1, as shown in FIG. (Determined by the quantum well structure (4,6) in the intermediate layer) of With / 4n _H It grows into the high reflectivity mirror layer 2 with a thickness of / 4n _L , and the period number of the Al _x Ga _1-x As / A1As high reflectivity mirror layer 2 is selected according to the structural conditions to determine the reflectance (period) The higher the number, the higher the reflectance).

Looking at the schematic structure of the whole structure as described above, the layer formed of P ⁺ -iN ⁺ -iP ⁺ -... (3,4,5,6,7) and semiconductor high on the high reflectivity mirror layer 2 in order A mirror layer 8 of lower frequency than the mirror layer 2 having a reflectance lower than that of the reflecting mirror layer 2 (which can be realized by adjusting the number of cycles) or the upper mirror layer 8 of the semiconductor / air plane It consists of.

The P ⁺ electrode was formed of a highly doped p-type Al _x Ga _1-x As layer (3,7), and the p-type impurity diffused into the multiple quantum well (MQW) layer above each of them. An undoped Al _x Ga _1-x As buffer layer (4,6) was formed to prevent. The intrinsic regions 4 and 6 are composed of an Al _x Ga _1-x As barrier layer and a GaAs well layer, which consist of a multi-quantum well structure and a buffer layer for protecting the layer.

The N ⁺ electrode layer 5 was formed of a highly doped n-type Al _1-x Ga _x As layer and an undoped Al _x Ga _1-x As buffered optically active layer to prevent the diffusion of impurities on the upper and lower surfaces thereof. 4,6).

The uppermost part of the device structure was formed with an upper layer 8 to obtain a mirror effect on the operating wavelength.

In FIG. 1, the entire optical logic device structure can be sufficiently depleted by the built-in potential formed by the positive (P ⁺ , N ⁺ ) semiconductor electrode to operate at a no-voltage (4, 6) The thickness and cycle number of the quantum well structure of the layer should be adjusted. In addition, the structure must be adjusted to have a resonance condition by placing the upper mirror film. That is, the total thickness (L) between the two mirrors is adjusted to be an integer multiple (m) of the half wavelength divided by the average refraction (n _avg ) in the resonator (L = m / (2n _avg )) In addition, the number of quantum wells required for thickening the light absorbing layer to obtain high optical signal readout ratio and no-voltage operation was distributed to the diode interlayers in consideration of the no-voltage operating conditions to solve the light trapping effect of the resonator.

As an example of FIG. 1, a diode intermediate layer is about 0.35 with respect to a 50 _- kV Al _x Ga _1-x As / 100-GaAs quantum well structure (x-0.04). In the case of m, 15 cycles are distributed to two layers of pin diodes, and the optical signal reflectivity of 25% in the on state and 1% in the off state can be obtained from the asymmetric resonator theory. At this time, the higher the intrinsic potential value (generally regarded as about 1.5V in the example of the present invention) formed by P and N semiconductor electrode layers (heavy doped Al _x Ga _1-x As), which are important variables, the thickness of the intermediate layer is increased. This can increase the number of quantum wells of the intermediate absorbing layer, thereby improving the optical signal ratio and the light saturation characteristics.

FIG. 2 is an example of a cross-sectional view of an optical device structure in which two layers of diodes are laminated using the multilayer structure shown in FIG. 1 of the present invention. Since the structure of the optical device has a stacked diode structure, that is, PiNiP, in order to implement a voltage-free optical bistable logic device using a diode optical modulator, two modulators having a stacked structure must be electrically connected. The same structure can be used.

Unlike the electrical connection of an externally applied voltage type optical device using S-SEED (symmetric self electrooptic effect device) having a conventional PiN structure, it exposes the electrode layers necessary for electrical connection and connects them in series without external power to both optical modulators. shall. The insulating film 9 is required as shown in FIG. 2 for the necessary insulation between the electrodes or between the semiconductor electrode and the metal wiring, and the p-omic metal 10 and the n-omic metal 11 are formed of a P-type semiconductor and an N-type semiconductor electrode, respectively. It is a metal forming an ohmic junction.

FIG. 3 is a plan view of a voltageless optical logic device using an optical modulator in which two diodes of FIG. 2 are stacked. The device is fabricated in two mesa (MESA) processes to form a first mesa structure 31 and a second mesa structure 32, and a high reflectivity mirror layer 2, which is an undoped lower mirror layer, for electrical isolation between diodes. Isolate up to a portion of the surface. The insulating film SiNx (9) is used to insulate the metal wiring 12 between the electrodes, and the ohmic metal film is made of p-omic metal 10 and n-omic metal 11 for the exposed semiconductor electrode, respectively. The two resonant-layered diode modulator structures are self-connecting without an external applied voltage as shown in FIG. The entrance and exit of the optical signal is formed by opening a window 8 which is an upper mirror layer.

Since the voltage-free optical bistable logic device does not need a metal wiring for external voltage application as shown in FIG. 3, the structure is very simple, and thus it is very easy to manufacture a two-dimensional array for fully optical parallel signal processing. In addition, the present invention does not require an externally applied voltage as compared with the prior art described above. That is, the present invention combines a resonance structure and a stacked pinip diode structure to divide a predetermined thickness (1) necessary for high optical signal contrast ratio by the number of stacked diodes to obtain l / n to obtain its own diode bias without an externally applied voltage Va. It is possible to obtain a sufficiently large driving electric field only by (Vb). That is, the present invention has an electric field of (nVb) / l, where n is the number of stacked diodes, so that the driving electric field is sufficiently large. Therefore, the present invention obtains a large signal ratio even without an externally applied voltage, and since there is no external voltage Va, the switching energy, which is a physical characteristic of the device, is greatly reduced, and thermal decay of the device performance due to photocurrent is greatly reduced. In addition, the voltage-free optical device of the present invention adopts a laminated structure and a resonance structure, and has an advantage of obtaining an appropriate optical signal difference and a high optical signal contrast ratio required by an optical signal processing system with sufficient electric field effect and sufficient light absorption only by the intrinsic potential. .

Claims (5)

A vertical structured optical modulator combining a resonance structure and a p-i-n-i-p stacked diode structure is driven by itself without an external power source to operate by its diode bias without an external voltage. The intermediate active layer in the fin diode structure determines the number of cycles of the quantum well so as to be fully operated by the intrinsic potential of the semiconductor PN junctions, and then the pin diode is repeatedly stacked in the vertical direction to increase the light sensitivity in the resonance structure. The structure of the voltage-free optical bistable logic device characterized in that it has. Growing a compound semiconductor multilayer mirror layer on the semi-insulating semiconductor substrate; A second process of forming a first conductive layer on the lower mirror layer formed in the first process; A third process of forming an optically active intermediate layer multiple quantum well layer on the first conductive layer formed in the second process; A fourth process of forming a second conductive layer on the layer formed in the third process by using a doping material having a polarity different from that of the doping material used for forming the first conductive layer; A fifth process of forming an optically active intermediate layer multiple quantum well layer on the second conductive layer formed in the fourth process; A sixth step of forming a first conductive layer of the second step on the well layer; And a seventh process of repeatedly performing the third and fourth processes sequentially to form an upper mirror layer at a predetermined thickness L from the lower mirror layer of the first process. Method of manufacturing the device. The n-semiconductor electrode layer (or p-semiconductor) according to claim 3, wherein the first conductive layer is formed of a p-semiconductor electrode layer (or n-semiconductor electrode layer), and the second conductive layer is different from the first conductive layer. An electrode layer). The method of claim 3, wherein a distance between the upper mirror layer formed in the seventh process and the lower mirror layer formed in the first process is formed within a range satisfying a resonance condition.