KR20000056928A - Photodetector for wavelength and optical power - Google Patents

Abstract

PURPOSE: An optical detector capable of detecting wavelength and optical current simultaneously is provided to measure wavelength of various input light sources and optical current simultaneously by growing a plurality of InGaAsP optical absorption layers having different band gaps to have wider optical absorption wave length band width. CONSTITUTION: An optical detector capable of detecting wavelength and optical current simultaneously includes a plurality of InGaAsP optical absorption layers(10) having different band gaps, a clad layer, a InGaAs optical absorption layer(7) and a clad layer stacked on an electronic InP semiconductor substrate(6) in sequence and an upper hole type resistant contact metal layer(2) additionally contacting the clad layer on the InGaAsP optical absorption layers, so that optical current according to the strength of partial light beams radiated from an optical fiber is measured by the upper hole type resistant contact metal layer and a middle hole type resistant contact metal layer(8) and the wave length of the remaining light beams is measured by the middle hole type resistant contact metal layer and a lower electronic resistant contact metal layer(5).

Description

Photodetector for wavelength and optical power

The present invention relates to a new photodetector capable of measuring the wavelength and light intensity of incident light by using a property in which the light absorption coefficient of the material is changed according to the wavelength incident in the wavelength band near the band gap of the semiconductor.

Currently living in a highly information society, wavelength division multiplexing technology, which transmits multiple wavelength signals simultaneously to one optical fiber, is one of the important technologies in optical communication systems to cope with ever-increasing communication demand. At present, it is essential to check the wavelength of the light source used for the optical communication and measure the light intensity.

1 is a diagram illustrating a conventional wavelength identification method having an InGaAsP mixture having a single bandgap or an InGaAsP / InGaAsP multi-quantum well structure. Although the basic structure is the same as that of a general hole-intrinsic-electron (p-i-n) junction photodetector, the material of the intrinsic absorption layer is composed of InGaAsP mixture or InGaAsP / InGaAsP multiquantum well (3).

FIG. 2 shows an integrated photodetector structure in which the InGaAsP absorber layer photodetector structure is vertically integrated with the photodetector of the InGaAs absorber layer so that no additional InGaAs photodetector is required. That is, in the photodetector, an InGaAsP mixture or an InGaAsP / InGaAsP multiquantum well absorbing layer 3, a cladding layer, an InGaAs absorbing layer 7, and a cladding layer are successively stacked on the electronic InP semiconductor substrate 6, and the multi-quantum On top of the well light absorbing layer 3 is further formed a hole-type resistive contact metal layer 8 of the photodetector in contact with the cladding layer.

However, when the intrinsic absorption layer has a single bandgap, it is expected that the absorption wavelength band where the light absorption is linear in the vicinity of the bandgap will be narrow, and the measurable wavelength may also be 1.3 µm or 1.55 µm, which is a representative wavelength used in an optical communication light source. Only one wavelength of can be measured. Therefore, in order to solve this problem, in the present invention, by stacking multiple InGaAsP absorbing layers having different bandgaps in succession, a plurality of light sources used in a multi-division multiplexing optical communication system having a broader absorption wavelength band than a photodetector having a single absorbing layer are provided. A photodetector having an InGaAsP absorbing layer characterized by simultaneously measuring wavelengths is proposed.

When using a photodetector having a single light absorbing layer having a conventional InGaAsP mixture or an InGaAsP / InGaAsP multi-quantum well structure, the absorption wavelength band is expected to be narrow. As an experimental example, a band gap of 1.55 μm as shown in FIG. The relationship of the photocurrent change in the InGaAsP absorption layer with the change of wavelength of the input light measured using a single InGaAsP absorption layer with was investigated. The wavelength band where the light absorption is made is very narrow, about 20 nm, and crystal growth of the InGaAsP absorption layer having the band gap where light absorption is made in the wavelength band exactly 1.55 μm is very difficult in FIG. 3.

In the present invention, instead of a single light absorbing layer of InGaAsP mixture or InGaAsP / InGaAsP multi-quantum well structure, a photodetector having a multi-layered InGaAsP absorbing layer having a plurality of consecutively stacked InGaAsP absorbing layers, and an InGaAsP absorbing layer and an InGaAs absorbing layer vertically. An integrated photodetector is proposed to implement a photodetector that can measure multiple wavelengths simultaneously with a wide absorption wavelength band.

In addition, in the present invention, a photodetector composed of an InGaAs absorbing layer measuring a photocurrent that varies with light intensity and a photodetector composed of an InGaAsP absorbing layer measuring a change in wavelength of incident light are independently manufactured and packaged together. A photodetector capable of simultaneously measuring light intensity is also proposed.

As can be seen from the experimental results of FIG. 3, although the wavelength band of linearly absorbing light of a photodetector composed of a single absorbing layer is very narrow, about 20 nm, several InGaAsP absorbing layers having different band gaps proposed in the present invention are stacked. The photodetector having a wide light absorption wavelength band that changes linearly can be manufactured. Therefore, in order to implement the photodetector having the wide light absorption wavelength band, a lamination technique for growing an InGaAsP absorption layer having different band gaps is absolutely necessary. Similarly, in order to implement a photodetector capable of measuring several wavelengths simultaneously, such as 1.3 μm and 1.55 μm, a lamination technology for growing multiple InGaAsP absorbing layers having different band gaps around one wavelength band is also very important. Do.

On the other hand, when the InGaAs light absorbing layer and the InGaAsP light absorbing layer are vertically stacked in succession, the leakage current in the two absorbing layers increases in proportion, which causes a decrease in the reception sensitivity of the photodetector element. Therefore, these two photo devices, namely, a photodetector composed of an InGaAs absorption layer for measuring photocurrent and an InGaAsP absorber layer for measuring the wavelength of incident light, are fabricated independently and packaged together to minimize leakage currents of the two photodetectors. The reception sensitivity can be improved. In order to minimize the leakage current may also be affected by the manufacturing process of the photodetector element, but at present, since most leakage current is determined by the stacking technology of the absorption layer, the stacking technology of the InGaAs absorption layer and InGaAsP absorption layer may be very important. .

1-Schematic cross section of a conventional photodetector structure with wavelength dependence

Fig. 2-Schematic cross-sectional view of an optical device structure incorporating a conventional photodetector having a wavelength dependency and a photodetector without a wavelength dependency.

FIG. 3-Curve of Photocurrent Change with Wavelength of Input Light in InGaAsP Photodetector with Single Light Absorption Layer

4-schematic cross-sectional view showing the structure of a semiconductor photodetector having an InGaAsP light absorption layer;

5 is a schematic cross-sectional view of an InGaAsP absorption layer photodetector structure having multiple band gaps and a photodetector integrated vertically with the photodetector of the InGaAs absorption layer.

6A-Schematic cross-sectional view of a structure in which a photodetector composed of an InGaAs absorbing layer for measuring photocurrent and a photodetector composed of an InGaAsP absorbing layer for measuring wavelengths are independently manufactured and packaged together on the same substrate

6B-A schematic cross-sectional view of a structure in which a photodetector composed of an InGaAs absorbing layer for measuring photocurrent and three photodetectors composed of an InGaAsP absorbing layer for measuring wavelengths are independently manufactured and packaged together on the same substrate.

<Explanation of symbols for main parts of drawing>

1: anode of photodetector 2: hole-type ohmic contact metal layer of photodetector

3: InGaAsP or InGaAsP / InGaAsP multi-quantum well structure absorption layer of photodetector

4: cathode of photodetector 5: electronic resistive contact metal layer of photodetector

6: Electronic InP Semiconductor Substrate 7: InGaAs Absorption Layer of Photodetector

8: hole resistive contact metal layer of photodetector

9: Hole InP Layer / Hole InGaAs Resistive Contact Layer

10: common anode of photodetector

11: Multiple InGaAsP Absorption Layers with Different Band Gap

12: InGaAs absorption layer photodetector

13: InGaAsP Photodetectors with Single or Single Bandgap with One or More Wavelength Bands or with Different Bandgaps

14: heat sink

15: InGaAsP photodetector with single bandgap or different bandgap in 1.3 μm or 1.55 μm wavelength band

Detailed description of the photodetector proposed in the present invention will be referred to the accompanying drawings. Figure 4 is a schematic diagram showing the structure of the InGaAsP light absorption layer for realizing the structure proposed in the present invention.

In the present invention, the intrinsic light absorbing layer has a structure of several InGaAsP absorbing layers 3 having different band gaps instead of the intrinsic light absorbing layer having a conventional InGaAsP compound or an InGaAsP / InGaAsP multi-quantum well. Multiple layers of InGaAsP light having different band gaps as absorbing layers of the photodetector in a structure consisting of an intrinsic InGaAsP absorbing layer on the electronic InP absorbing layer 6 and a hole InP absorbing layer and a hole InGaAs resistive contact layer 9 thereon. Stacking with the structure of the absorbing layer 3 reduces the need for difficult growth of the InGaAsP absorbing layer having the required accurate absorbing wavelength band, thereby facilitating stacking of the InGaAsP absorbing layer. In addition, it has a broad absorption wavelength band for the wavelength of incident light in the 1.3 μm or 1.55 μm wavelength band, thereby making it possible to extend the wavelength measurement range of the photodetector having the InGaAsP absorption layer than that of a conventional wavelength measurable photodetector. If the wavelength band of the light source enters the input light simultaneously at 1.3 μm or 1.55 μm instead of a single wavelength, when the InGaAsP light absorption layer is grown in FIG. 4, multiple layers of InGaAsP having different band gaps around the wavelength bands of 1.3 μm and 1.55 μm, respectively Using a photodetector grown with a light absorption layer, various wavelengths such as 1.3 μm and 1.55 μm can be simultaneously measured.

The present invention proposes an integrated photodetector having a simple system configuration without the need for an additional InGaAs photodetector by vertically integrating multiple InGaAsP absorption layer photodetector structures having different band gaps and photodetector structures of the InGaAs absorption layers as shown in FIG. 5. do.

That is, in the photodetector, a plurality of InGaAsP light absorbing layers 10, cladding layers, InGaAs light absorbing layers 7 and cladding layers having different band gaps are sequentially stacked on top of the electronic InP semiconductor substrate 6, The hole-type ohmic contact metal layer 2 of the photodetector contacting the clad layer on the upper part of the multiple light absorption layers 10 having different band gaps is further configured. When the InGaAsP absorption layer photodetector structure and the InGaAs absorption layer photodetector are vertically integrated as shown in FIG. 5, an InGaAs absorption layer is integrated on the InGaAsP absorption layer photodetector structure or an InGaAsP absorption layer is vertically integrated on the InGaAs absorption layer structure.

The operation principle of the photodetector in which the InGaAsP absorption layer and the InGaAs absorption layer having different band gaps are vertically integrated is as follows. In FIG. 5, part of the light incident through the optical fiber is absorbed by the InGaAs absorbing layer 7 irrespective of the wavelength so that a photocurrent according to the intensity of the input light is transmitted to the intermediate hole-type ohmic contact metal layer 8 and the hole-type ohmic contact metal layer 2 above. The wavelength of the remaining input light absorbed in the absorption wavelength band of the absorption layer 3 of the InGaAsP structure having wavelength dependence on the incident light is determined by the intermediate hole-type resistive contact metal layer 8 and the electron-resistant resistive contact metal layer 5 below. Is measured from

FIG. 6 shows that an InGaAs photodetector and one or more wavelength bands are formed on the same heat emission substrate by independently fabricating a photodetector including an InGaAs absorbing layer for measuring photocurrent and an InGaAsP absorbing layer for measuring the wavelength of input light. InGaAsP photodetector with single-band bandgap having different bandgap or different bandgap (FIG. 6A) or one InGaAs photodetector with single-band bandgap with 1.3 or 1.55 μm wavelength band or with different bandgap (FIG. 6B) Figure suggests packaging together. This method is similar to the operation principle of the photodetector in which the InGaAs absorbing layer and the InGaAsP absorbing layer are vertically integrated. However, the two photodetectors are packaged together by fabricating each photodetector independently. The only way is different. This packaging method has the advantage that although the light incident from the optical fiber has to be coupled (coupled) to two independent photodetectors, although the optical coupling efficiency is low, its reception sensitivity can be improved.

As described above, when the intrinsic absorption layer has only one bandgap, the absorption wavelength band where the light absorption is linear in the vicinity of the bandgap is narrow and the absorption layer growth is difficult, and the wavelength is also mainly used in optical communication light sources. Only the wavelength of either [mu] m or 1.55 [mu] m can be measured. In order to solve this problem, in the present invention, not only can measure the wavelength of one or several external input light source but also the photocurrent can be measured at the same time, instead of the conventional light absorption layer having a single band gap By growing InGaAsP light-absorbing layers with different bandgaps, InGaAsP light-absorbing layers can be grown more easily than in the past, and the wavelength of optical communication light sources having a wide light absorption wavelength band and various light wavelengths can be measured at various wavelengths. In addition, by integrating vertically below the InGaAs absorbing layer or the InGaAs absorbing layer to measure the photocurrent varying according to the light intensity, a photodetector capable of simultaneously measuring wavelengths and photocurrents of various input light sources can be fabricated.

Claims (7)

In a photodetector capable of measuring the wavelength of an external input light source, an absorption layer in which multiple intrinsic InGaAsP absorption layers having different bandgaps (compositions) are stacked on an electronic InP semiconductor substrate and a hole on the intrinsic InGaAsP absorption layer It has an integrated crystal growth layer structure having a PIN photodetector structure consisting of an InP absorbing layer, a hole InGaAs resistive contact layer, and a hole resistive contact metal layer, and a hole-type resistive contact grown on the hole-type InGaAs resistive contact layer of the photodetector. The anode of the photodetector is connected to the metal layer, and the cathode of the photoresist is formed on the electronic resistive contact metal layer grown on the electronic InP semiconductor substrate of the photodetector. rescue The method of claim 1, wherein in the growth of the intrinsic InGaAsP absorbing layer whose light absorption coefficient is different depending on the wavelength, the InGaAsP absorbing layer having a different band gap based on the wavelength band of 1.3 ㎛ on the electronic InP semiconductor substrate as a plurality of layers InGaAsP absorber layer is grown continuously and the InGaAsP absorber layer having different band gaps is vertically grown on the InGaAsP absorber layer in the vertical direction. It has an integrated crystal growth layer structure having an InGaAs resistive contact layer and a PIN photodetector composed of a hole resistive contact metal layer, and is formed of a hole resistive contact metal layer grown on the hole-type InGaAs resistive contact layer of the photodetector. Photodetector instrument applicable to both 1.3 μm and 1.55 μm wavelength bands article The inGaAs resistive contact layer and the intrinsic InGaAs of claim 1, wherein the absorbing layer is formed by successively stacking intrinsic InGaAsP absorbing layers having different band gaps on an electronic InP semiconductor substrate. A photodetector having an integrated crystal growth layer structure having an absorption layer, having an integrated photodetector structure consisting of an electron InP absorption layer on the intrinsic InGaAs absorption layer, and having an InGaAs absorption layer and a photodetector having an InGaAsP absorption layer in common The structure of the photodetector characterized in that it has an electronic resistive contact metal layer of the photodetector having an InGaAsP absorbing layer and an electronic resistive contact metal layer of the photodetector having an InGaAs absorbing layer, respectively. The absorbing layer according to claim 1, wherein an intrinsic InGaAs absorbing layer is grown on an electronic InP semiconductor substrate, and a plurality of intrinsic InGaAsP absorbing layers having different hole gaps and intrinsic InGaAsP absorbing layers having different band gaps are sequentially stacked on the intrinsic InGaAs absorbing layer. Has a structure of integrated crystal growth layer having a photodetector structure consisting of an electron InP absorber layer on the intrinsic InGaAsP absorber layer, and a photodetector having an InGaAs absorber layer and a photodetector having an InGaAsP absorber layer in common. The structure of a photodetector having an electronic resistive contact metal layer of a photodetector having an InGaAsP absorbing layer and an electronic resistive contact metal layer of a photodetector having an InGaAs absorbing layer connected to the resistive contact metal layer According to claim 1, InGaAsP absorption layer photodetector structure having a different bandgap or single bandgap for measuring the wavelength change of the input light and the InGaAs absorption layer consisting of the InGaAs absorption layer for measuring the photocurrent changes by the light intensity, each independently After fabricating and arranging the side surfaces of the two types of photodetectors in contact with each other on one heat-dissipating substrate, the electronic resistive contact metal layer of the photodetector having the InGaAs absorbing layer and the photoresist having the InGaAsP absorbing layer. Is commonly connected to the electron-resistive contact metal layer, and each of the photodetector active layer regions are formed independently of the hole-resistant resistive contact metal layer and packaged together on the heat emission substrate. The InGaAsP absorption layer photodetector structure applicable to both 1.3 μm and 1.55 μm wavelength bands having different bandgaps or single bandgaps for measuring wavelength variations of input light, and InGaAs for measuring photocurrents varying with light intensity. Each of the photodetector structures composed of absorbing layers was independently fabricated, and the side surfaces of the two types of photodetectors were placed on one heat-emitting substrate in contact with each other, and then the electronic resistive contact metal layer and the InGaAsP absorbing layer of the photodetector having an InGaAs absorbing layer. The electron-resistant resistive contact metal layer of the photodetector having a common connection to the electron-resistant resistive contact metal layer and each of the above-described active layer regions of each photodetector each independently forms a hole-resistant resistive contact metal layer on the heat-emitting substrate. As far as applicable to both InGaAs photodetectors and 1.3 μm and 1.55 μm wavelengths The packaging method of the photodetector, characterized in that the packaging with the InGaAsP optical detector The method of claim 1, wherein the absorption layer for measuring the wavelength change of the input light, the InGaAsP absorption layer having a different bandgap of 1.3 ㎛ wavelength band on the electronic InP semiconductor substrate continuously growing in multiple layers or having a single bandgap Independently fabricate the photodetector structure in which the InGaAsP absorption layer is grown and the photodetector structure in which the InGaAsP absorption layer having the different bandgap of 1.55 ㎛ wavelength is continuously grown in multiple layers or the InGaAsP absorption layer with the single bandgap is grown. Also, a photodetector composed of an InGaAs absorbing layer capable of measuring a photocurrent varying with light intensity is manufactured separately, and a single photodetector having an InGaAs absorbing layer on one heat-emitting substrate and InGaAsP in which multiple layers of different bandgaps are continuously grown. Phase with absorption layer or InGaAsP absorption layer with single bandgap Two types of photodetectors each having an InGaAsP absorbing layer having a wavelength range of 1.3 μm and 1.55 μm of are independently placed side by side in contact with each other, and then one InGaAs photodetector and two types of InGaAsP photodetectors are each provided with electronic resistive contacts. The above-mentioned connection is common to a metal layer, and the hole-type resistive contact metal layer is formed in the active layer region of one InGaAs photodetector, and the hole-type resistive contact metal layer is commonly formed in each active layer region of the two other InGaAsP photodetectors. A method of packaging a photodetector comprising packaging one InGaAs photodetector and two InGaAsP photodetectors having both 1.3 μm and 1.55 μm wavelength bands on a heat emitting substrate