KR20170086418A - UV light detecting device - Google Patents

Abstract

An ultraviolet ray detecting element is provided. This ultraviolet detecting element comprises a substrate; A buffer layer located on the substrate; A light absorbing layer disposed on the buffer layer; A capping layer disposed on the light absorbing layer; And a Schottky layer located in a partial region on the capping layer, wherein the capping layer has a larger energy band gap than the light absorption layer.

Description

UV light detecting device < RTI ID = 0.0 >

The present invention relates to an ultraviolet ray detecting element, and more particularly to an ultraviolet ray detecting element having a high detection accuracy for light in an ultraviolet ray region.

In semiconductor devices, GaN (gallium nitride), SiC (silicon carbide) and the like, which are suitable for energy band gap ultraviolet ray detection, are widely used.

Especially, in the case of a GaN-based device, Schottky junction, MSM (Metal-Semiconductor-Metal) type and PIN type devices are mainly used. Especially, in the case of a gallium nitride ultraviolet detector, It is difficult to secure the characteristics of the high p-type AlGaN layer and the reproducibility is not ensured. On the other hand, in the case of the Schottky junction type, the p-AlGaN layer does not need to be grown.

At this time, in the case of a general GaN-based detection device, a buffer layer is grown on a different substrate and a light absorption layer is formed on the buffer layer. Due to the use of a different substrate, many defects are present in the buffer layer.

If the light absorbing layer is grown on the buffer layer with many defects, defects of the light absorbing layer are also directly affected by the buffer layer, so that different photocurrent characteristics can be seen on the same wafer. In addition, since the density of defects of the light absorbing layer is not uniform, the ultraviolet light reactivity and the fine generated current value due to the visible light reaction have different values depending on the devices, so that productivity, reproducibility, yield and detection accuracy are lowered, have. Furthermore, when the ultraviolet sensor is fabricated with a Schottky junction structure, the metal layer may be placed on the light absorption layer to cause a decrease in ultraviolet light reactivity and leakage current depending on the thickness of the Schottky layer and the interface characteristics on the light absorption layer.

In addition, the Schottky barrier property may be deteriorated by the leakage current when the Schottky junction is formed on the light absorption layer with many crystal defects, so that the characteristics of the photodetecting device with high efficiency may not be obtained.

An object of the present invention is to provide an ultraviolet ray detecting element with improved Schottky characteristics.

Another object of the present invention is to provide an ultraviolet ray detecting element which is improved in light reactivity and leakage current characteristics by applying a capping layer having a larger energy band gap than a light absorbing layer.

Another object of the present invention is to provide an ultraviolet ray detecting element capable of improving electrostatic discharge (ESD) characteristics and relieving stress in a light absorbing layer and blocking reaction light other than ultraviolet light.

The objects of the present invention are not limited to those described above, and other objects and advantages of the present invention which are not mentioned can be understood by the following description.

According to an embodiment of the present invention, A buffer layer located on the substrate; A light absorbing layer disposed on the buffer layer; A capping layer disposed on the light absorbing layer; And a Schottky layer located in a partial region on the capping layer, wherein the capping layer has a larger energy band gap than the light absorption layer.

The ultraviolet detecting element according to the embodiment of the present invention includes a capping layer having a larger energy bandgap than the light absorbing layer, thereby maximizing the Schottky characteristic and improving the light reactivity and improving the leakage current characteristic.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a plan view of an ultraviolet ray detecting element according to an embodiment of the present invention.
2 is a cross-sectional view of an ultraviolet ray detecting element according to an embodiment of the present invention.
3 shows an example of improvement of the Schottky characteristic according to the embodiment of the present invention.
4 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.
5 shows an energy band diagram of an ultraviolet detecting element according to an embodiment of the present invention.
6 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention.
7 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.
8 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention.
9 is a sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.
10 shows an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention.
11 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.
12 shows an energy band diagram according to another embodiment of the present invention.
13 is a sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.
14 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

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

FIG. 1 is a plan view of an ultraviolet ray detecting element according to an embodiment of the present invention, and FIG. 2 is a sectional view of an ultraviolet ray detecting element taken along a perforated line A-A 'of FIG.

1 and 2, an ultraviolet detecting device according to an embodiment of the present invention includes a substrate 110, a buffer layer 120, a light absorbing layer 130, a capping layer 140, a Schottky layer 150, Layer 160 as shown in FIG. In addition, the ultraviolet ray detecting element may further include a first electrode 170 and a second electrode 180.

The substrate 110 is for growing a semiconductor single crystal, and includes sapphire, Zinc oxide (ZnO), gallium nitride (GaN), silicon carbide (SiC), and aluminum nitride (AlN) may be used. Particularly, the substrate 110 has a high degree of orientation, and a sapphire substrate free of scratches or marks due to accurate polishing can be mainly used.

The buffer layer 120 may include a first buffer layer 121 formed on the substrate 110 and a second buffer layer 122 formed on the first buffer layer 121. The second buffer layer 122 may include a region where the second electrode 180 is contacted, as described below, and thus may be referred to as a contact layer.

The first buffer layer 121 may include, for example, a GaN layer. In the first buffer layer 121, the substrate 110 is placed on the susceptor of the MOCVD apparatus, the impurity gas in the reaction tube is removed by reducing the pressure inside the reaction tube to 100 torr or less, The surface of the dissimilar substrate 110 was thermally cleaned, the temperature was lowered to 500 to 600 ° C, preferably to 550, and a Ga source and an ammonia (NH ₃ ) gas And the like. At this time, the overall gas flow of the reaction tube can be determined by hydrogen (H ₂ ) gas.

The first buffer layer 121 may be formed to have a thickness of at least 25 nm or more to ensure crystallinity and optical and electrical characteristics of the second buffer layer 122 grown on the first buffer layer 121.

The first buffer layer 121 can improve the crystallinity of the second buffer layer 122 and thus the optical and electrical characteristics of the second buffer layer 122 can be improved. In addition, when the substrate 110 is a heterogeneous substrate such as a sapphire substrate, the first buffer layer 121 may serve as a seed layer on which the second buffer layer 122 can be grown.

The second buffer layer 122 may be grown at a relatively higher temperature than the first buffer layer after the growth of the first buffer layer 121. The second buffer layer 122 can be grown, for example, by raising the temperature of the susceptor to 1000 to 1100 캜, preferably to 1050. If the temperature is less than 1000, the optical, electrical, and crystallographic characteristics are deteriorated. If the temperature exceeds 1100, the surface roughness may become coarse and the crystallinity may be deteriorated.

The second buffer layer 122 may comprise a material similar to the first buffer layer. The second buffer layer may comprise, for example, a GaN layer. The nitride-based semiconductor exhibits n-type characteristics without doping, but may also be doped with Si for the n-type effect. When the second buffer layer 122 is n-type doped including Si, the doping concentration of Si may be 1 x 10 ⁸ or less. The second buffer layer 122 may have a thickness of about 2.5 占 퐉.

In addition, the second buffer layer 122 may be formed by growing a 1.5-μm thick undoped GaN layer on the first buffer layer 121.

The light absorption layer 130 may be grown on the second buffer layer 122. [ The light absorption layer 130 may include a nitride semiconductor and may be grown on the second buffer layer 122 by selectively applying an element and a composition of the nitride semiconductor according to a wavelength of light to be detected in the light detecting element.

Light absorbing layer 130 according to an embodiment of the present invention is a layer that generates a flow of current by absorbing band in the ultraviolet ray region light, for example, _{Al x Ga 1 - x N (} 0 <x <0.7) layer, GaN layer Or an InGaN layer. Here, the energy band gap of the Al _x Ga _{1 -} may select the _{x N (0 <x <0.7} ) adequate light absorption in the ultraviolet wavelength range according to the highest layer to be detected by the InGaN layer using the lowest characteristic.

Specifically, the second buffer layer 122. After the growth of the Al _x Ga _{1 -} is the light absorbing layer 130 including the _{x N (0 <x <0.7} ) layer can be grown. In this case, the energy band gap of the light absorption layer 130 varies depending on the wavelength region of the light to be absorbed, and the light absorption layer 130 having a desired energy band gap can be grown by appropriately adjusting the Al content.

Or the light absorbing layer 130 including the GaN layer may be grown after the second buffer layer 122 is grown. At this time, the light absorption layer 130 including the GaN layer may be grown at about 1000 to 1100 ° C. Or the second buffer layer 122. After the growth of the In _y Ga _{1 -} can be a grown light absorbing layer 130 including the _{y N (0 <y <1} ) layer. At this time, the light absorption layer 130 including the In _y Ga _{1 - y} N (0 <y <1) layer can be grown at about 800.

The light absorption layer 130 may be grown to a thickness of 0.05 to 0.5 탆, and it is preferable that the light absorption layer 130 is grown to a thickness of about 0.15 탆 in consideration of the influence of cracks or the like. Further, the light absorption layer 130 may be composed of multiple layers, but it may be more effective to have a single layer in order to maximize the Schottky characteristic.

The capping layer 140 is grown on the light absorbing layer 130. The capping layer 140 serves to complement the Schottky layer 150, which will be described later, and can facilitate the obtaining of the Schottky characteristic of the Schottky layer 150.

The energy band gap of the capping layer 140 according to the embodiment of the present invention is larger than the energy band gap of the light absorption layer 130. [ The capping layer 140 is positioned on the light absorption layer 130 based on the direction in which the light is incident. Therefore, when the energy band gap of the capping layer 140 is smaller than the energy band gap of the light absorption layer 130, a part of the incident light can be absorbed by the capping layer 140, I can do it. Accordingly, the capping layer 140 according to the present invention may include a layer having a larger energy band gap than the light absorption layer 130.

For example, the light absorbing layer 130 is Al _x Ga ₁ as previously reviewed _- After growth of the _{x N (0 <x <0.7} ) when containing layer, the capping layer 140 is, for example, light absorbing layer 130 , above the higher Al composition Al Ga _{1 k1} than the light absorption layer _{it may} be grown to _{k1 N (0 <k1 <1} ) layer. The capping layer 140 may be formed by growing an Al source at the same growth temperature as that of the light absorption layer 130, for example, 1000 to 1100 DEG C, after the growth of the light absorption layer 130. In this case, supplied may be grown by _k2 Al Ga _{1 -k2} N layer (0 <k2 <1). As another example, the light absorption layer 130 in this case comprises the InGaN layer, the capping layer 140 is a GaN layer and / or Al Ga _{1 k3 - k3} can be grown N layer (0 <k3 <1).

The capping layer 140 may have a thickness, for example, 1 nm to 10 nm, at which a tunneling effect can occur. If the thickness of the capping layer 140 is too thick, the capping layer can act as a light absorbing layer. The growth temperature of the capping layer 140 may be the same as or higher than the growth temperature of the light absorption layer 130.

The Schottky layer 150 is formed on a portion of the capping layer 140. The Schottky layer 150 may include a metal layer and may include any one of ITO, Ni, ATO, Pt, W, Ti, Pd, Ru, Cr and Au. In particular, the Schottky layer 150 may be formed of Ni having a high ultraviolet light transmittance. In this case, since the ultraviolet light transmittance decreases with an increase in the thickness, the Schottky barrier layer 150 may have a thickness of about 3 nm- 10 nm.

Metal layer of schottky layer 150 is _{Al x Ga 1 - x N (} 0 <x <0.7) layer, GaN layer or an _{In y Ga1-yN (0 <} y <1) light absorption layer 130 consisting of a layer and the short A Schottky junction can be formed. A reverse bias voltage may be applied to the Schottky layer 150 and the light absorption layer 130 in an operation mode in which the ultraviolet detection element detects light. The magnitude of the value of the current which changes in accordance with the intensity of the incident light is larger than the reverse region in the 0V (volt) region, so that the ultraviolet detecting element can operate more properly in the reverse region.

As described above, the capping layer 140 may be positioned between the light absorption layer 130 and the Schottky layer 150, and the energy band gap of the capping layer 140 according to the present invention may be the same as that of the light absorption layer 130 Can be larger than the energy bandgap. The capping layer 140 having a large energy bandgap can improve the Schottky property due to the bonding between the light absorption layer 130 and the Schottky layer 150.

3 shows an example of improvement of the Schottky characteristic according to the embodiment of the present invention.

Figure 3A shows a current-voltage curve of a Schottky junction according to the prior art. The light absorption layer 130 may have poor crystallinity due to various factors such as a low growth temperature, and a normal Schottky barrier may not be formed when the crystallinity of the light absorption layer 130 is poor. 3A, the IV curve of the Schottky junction in this case shows that the maximum voltage that can be sustained when the reverse bias is applied in the reverse region, that is, the maximum reverse voltage Vbr (or breakdown voltage) Characteristics may cause a problem that the leakage current value rapidly increases even with a small reverse bias voltage. In this case, the ultraviolet detecting element may malfunction due to a leakage current.

FIG. 3B shows the I-V curve of the Schottky junction to which the capping layer 140 according to the present invention is applied. According to the embodiment of the present invention, the I-V curve disclosed in FIG. 3A can be modified into a shape as shown in FIG. 3B due to the capping layer 140 having a large energy band gap. That is, FIG. 3B shows that the Schottky barrier can be formed high due to the capping layer 140, thereby improving the leakage current characteristic of the I-V curve. The IV curve in FIG. 3B can be improved in the IV curve linearity in the reverse bias region as compared with the IV curve in FIG. 3A, and the maximum reverse voltage Vbr 'is increased. Accordingly, even in a relatively large reverse bias voltage, Can be minimized. Accordingly, the reverse bias that can be applied to the ultraviolet detecting element can be made larger.

The depletion layer formed in the light absorption layer 130 under the Schottky layer 150 can be widened by increasing the reverse bias application and the photoreaction efficiency of the ultraviolet detection element can be improved thereby . That is, since the depletion layer becomes larger due to the increase of the applied reverse bias, the electrostatic capacity of the ultraviolet ray detecting element becomes smaller and the response speed (or the reaction rate) can also be increased.

The insulating layer 160 may be formed to seal the Schottky layer 150 on the capping layer 140. For example, the insulating layer 160 may be formed to cover the Schottky layer 150 and cover a part of the capping layer 140 exposed to the periphery along the rim of the Schottky layer 150. That is, the insulating film layer 160 simultaneously contacts the Schottky layer 150 and a portion of the capping layer 140 to fix the Schottky layer 150 on the capping layer 140, Peeling phenomenon of the Schottky layer 150 due to the peeling can be prevented and reliability and yield of the ultraviolet detecting element 1 can be improved. The insulating layer 160 may be used as a protective layer against external static electricity. The insulating film layer 160 may include any one of a SiNx layer and a SiOx layer.

The insulating film layer 160 can make the Schottky layer 150 have a uniform thickness. The Schottky layer 150 may be a metal layer and may involve annealing during its formation. The heat treatment process can be performed at a temperature of, for example, approximately 200 to 300 ° C, and the characteristics of the connection between the Schottky layer 150 and the nitride semiconductor layer, that is, the capping layer 140, have. In such a heat treatment process, the Schottky layer 150 may be oxidized. For example, when the short base layer 150 is formed of a metal such as Ni, the Ni may be oxidized to NiOx through a heat treatment process, whereby the volume of the short base layer 150 may increase. It is apparent, however, that the short base layer 150 is not limited to Ni, may include other metals, and that these metals may also be oxidized in the heat treatment process.

In the case where the insulating layer 160 covering the Schottky layer 150 is not formed according to the prior art, Ni of the Schottky layer 150 is oxidized with external oxygen (for example, oxygen in the atmosphere) Lt; RTI ID = 0.0 &gt; NiOx &lt; / RTI &gt; The heat treatment by the method of supplying oxygen from the outside may cause the thickness of the Schottky layer 150 to be uneven. That is, the thickness of the Schottky layer 150 formed of Ni can be made non-uniform according to the degree of oxidation of each part. Unevenness in the thickness of the Schottky layer 150 may cause unevenness of light transmittance and reactivity, which may lower the reliability of the ultraviolet detecting element.

However, the insulating layer 160 according to the embodiment of the present invention covers the Schottky layer 150, and the heat treatment process after forming the insulating layer 160 maintains uniformity of the thickness of the Schottky layer 150 . That is, the insulating layer 160 can prevent the Schottky layer 150 from being connected to external oxygen. In addition, the insulating film layer 160 may contain oxygen itself, and may provide the oxygen contained therein to the schottky layer 150 in a limited and uniform manner. Accordingly, the insulating layer 160 can prevent the Schottky layer 150 from being irregularly and non-uniformly oxidized during the heat treatment process, resulting in uneven thickness. For example, the insulating film layer 160 covering the Schottky layer 150 may be formed of a SiOx layer. The oxygen contained in the insulating layer 160 may be limitedly and uniformly supplied to the Schottky layer 160 during the heat treatment process so that the oxidation reaction in the Schottky layer 150 may occur uniformly. As a result, although the volume of the Schottky layer 150 can be increased somewhat, the uniformity of the thickness can be maintained, and as a result, the light transmittance and uniformity of the reactivity of the ultraviolet detecting element can be maintained and reliability can be ensured.

The ultraviolet detecting element according to an embodiment of the present invention further includes a first electrode 170 disposed on the Schottky layer 150 and a second electrode 180 disposed on the exposed region of the buffer layer 120 can do.

The first electrode 170 may be formed on a part of the surface of the Schottky layer 150. The first electrode 170 may include a metal and may be formed of a plurality of layers. For example, the first electrode 170 may include a structure in which a Ni layer / Au layer is stacked.

Since the region where the first electrode 170 is formed on the Schottky layer 150 can not transmit light and can not serve as the Schottky layer 150, the first electrode 170 is formed to have a minimum area for wire bonding And the first electrode 170 according to the embodiment of the present invention is formed adjacent to the side surface of the Schottky layer 150 so as to face the second electrode 180 in the left and right direction. Referring to FIG. 1, the first electrode 170 includes a body portion 171, a pair of branch portions 172 branched in both directions of the body portion 171 to uniformly flow the current of the Schottky layer 150, ). It is advantageous to maximize the width of the Schottky layer 150 even in the device of the same size because the variation of the reaction current value by the ultraviolet light is large according to the optimum width of the Schottky layer 150.

In addition, the ultraviolet detecting element according to the present invention includes an insulating film layer 160 covering the Schottky layer 150. Therefore, in order to define the region in which the first electrode 170 is to be connected to the Schottky layer 150, the etching process for a part of the region of the insulating film layer 160 may be preceded.

The second electrode 180 may form an ohmic contact with the buffer layer 120 and may include a plurality of layers including a metal. For example, the second electrode 180 may include a Ni layer / Au layer.

The second electrode 180 may be formed on the second buffer layer 122 exposed by etching and etching the capping layer 140 and the light absorption layer 130 by dry etching or the like. At this time, the second electrode 180 and the second buffer layer 122 are formed to have an ohmic characteristic and may be etched to a portion of the second buffer layer 122 during etching.

The second electrode 180 may be formed in a portion of the second buffer layer 122 away from the first electrode 170 and may be formed in a central portion to uniformly flow the current, The shape need not be limited to one embodiment of the present invention.

4 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention. The cross-sectional view of FIG. 4 is a cross-sectional view taken along the perforated line A-A 'of FIG. 1, and further includes a low-current blocking layer 125 as compared with the cross-sectional view of FIG. Therefore, the detailed description of the same configuration will be omitted and the difference will be mainly described.

Referring to FIG. 4, the low current blocking layer 125 is grown on the buffer layer 120 at a lower temperature than the light absorbing layer 130. Here, the light absorbing layer 130 is _{Al x Ga 1 - x N (} 0 <x <0.7) can include a layer or a GaN layer, that the current blocking layer 125 is a single-Al _t Ga _{1 -t} N (0 < t < 1) layer. In addition, low-current blocking layer 125 may include a plurality of _{Al t1 Ga 1 -t1 N (0} <t1 <1) / Alt2Ga 1-t2 N (0 <t2 <1) layer is an Al content different . When the low-current blocking layer 125 includes a plurality of layers, each layer may have the same thickness or different thicknesses from each other, and the thickness of each layer and the number of layers may be appropriately selected as needed have.

The lamination structure of the nitride layers having different Al composition ratios can be provided by growing the respective nitride layers at different pressures. For example, low-current blocking layer 125, the _{Al t1 Ga 1 - t1 N (} 0 <t1 <1) layer and the _{Al t2 Ga 1 - t2 N (} 0 <t2 <1) layer is repeated comprising a laminate structure in the case of forming a multi-layer _{structure, Al t1 Ga 1 - t1 N} (0 <t1 <1) layer is grown in approximately 100Torr _{pressure, Al t2 Ga 1 - t2 N} (0 <t2 <1) layer is approximately 400Torr Lt; / RTI &gt; pressure.

At this time, if a different growth conditions in addition to the pressure the same, the more the grown Al _t1 at a pressure of _{Ga 1-t1 N (0 <} t1 <1) layer is further grown in a high pressure _{Al t2 Ga 1 - t2 N (} 0 <t2 &Lt; 1) layer.

Thus, the nitride layers grown at different pressures can have different growth rates due to differences in growth pressures. Since the nitride layers have different growth rates, it is possible to control the Al composition, the growth thickness, and the like even under the same growth conditions except for the pressure.

The entire thickness of the current blocking layer 125 is preferably formed to a thickness for blocking and controlling the flow of the low current generated by the visible light energy absorbed in the light absorbing layer 130. For example, the thickness of the low-current blocking layer may be 100 nm or less.

The low current blocking layer 125 may have a higher defect density than the light absorbing layer 130. [ This can be obtained by growing the low current blocking layer 125 at a lower temperature than the light absorbing layer 130. For example, a light absorbing layer 130 may be grown at about 1050 and a low current blocking layer 125 may be grown at a temperature of about 30 to 200 lower. The crystallinity of the light absorbing layer 130 formed on the low current blocking layer 125 is rapidly lowered so that the quantum efficiency of the light absorbing layer 130 is lowered It is preferable that the low current blocking layer 125 is grown within a temperature lower than the light absorption layer 130 by 200 degrees. When the low-current blocking layer 125 is grown at a lower temperature than the light absorption layer 130, the light-absorbing layer 130 has defect density such as dislocation, vacancy, etc. of a relatively higher density as compared with the light absorption layer 130, It is possible to prevent the movement of the electrons generated by the electron transporting layer and thus to have a blocking effect of the minute current and to have a uniform visible light reaction current throughout the wafer.

In the case of the ultraviolet detecting element according to an embodiment of the present invention, electrons generated in the light absorbing layer 130 by visible light are captured by the low current blocking layer 125, thereby preventing the elements from being driven by visible light to the utmost . As described above, the low current blocking layer 125 is grown at a lower temperature than the light absorbing layer 130, and has a higher defect density. The electrons generated by the visible light are much smaller than the electrons generated by the ultraviolet rays, and thus the electrons can be prevented sufficiently from the defects existing in the low current blocking layer 125. That is, the low current blocking layer 125 has a defect density higher than that of the light absorbing layer 130, thereby preventing migration of electrons generated by visible light.

By adding the low-current blocking layer 125, the intensity of the excitation of the buffer layer 120 in terms of PL (optical property) can be lowered and the sensitivity to visible light is lowered in terms of reactivity Characteristics can be shown.

On the other hand, since the number of electrons generated by irradiation of ultraviolet light to the light absorption layer 130 is much greater than the number of electrons generated by visible light, the current is not captured by the low current blocking layer 125 . Therefore, the ultraviolet detecting element of the present invention has a very low degree of reactivity with visible light, so that it can have a visible light response ratio to ultraviolet light as compared with general ultraviolet detecting elements.

In particular, the ultraviolet detecting element of the present invention has a visible light response ratio to ultraviolet rays of 10 ⁴ or more. Therefore, according to the present invention, an ultraviolet ray detecting element having high detection efficiency and reliability can be provided.

5 shows an energy band diagram of an ultraviolet detecting element according to an embodiment of the present invention. Specifically, it Figures 5a and 5b shows the energy band diagram of the layer of the ultraviolet detecting device of Figure 4, wherein the light absorbing layer 130 is Al _x Ga _{1 -} includes the _{x N (0 <x <0.7} ) layer.

Of _x N light-absorbing layer 130 including the (0 <x <0.7) _layer, it Figures 5a and Al _x Ga ₁ to common features to 5b contain than the energy band gap of the buffer layer 120 includes GaN layer high and the energy band gap, the Al ratio than the light absorption layer 130, a high Al _k1 Ga _{1 -} the energy band gap of the capping layer 140 including the _{k1 N (0 <k1 <1} ) layer is a light absorbing layer (130) Of the energy band gap.

Referring to FIG. 5A, the low-current blocking layer 125 has a structure in which Al _t Ga _{1 -t} N (0 <t <1) layers having different Al compositions are alternately stacked. When the Al composition of the low current blocking layer 125 is higher than that of the light absorbing layer 130 or when the Al composition of the low current blocking layer 125 is lower than that of the light absorbing layer 130, the cut off slope is changed . Referring to FIG. 5B, the low-current blocking layer 125 may be composed of a single layer Al _t Ga _{1 -t} N (0 <t <1). In this case, the energy band gap of the low-current blocking layer 125 may be larger than that of the light absorbing layer 130.

6 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention. 6A and 6B show the energy band diagram of each layer of the ultraviolet detecting element of FIG. 4, and there is a difference in that the light absorbing layer 130 includes a GaN layer as compared with FIG.

6A and 6B, the energy band gap of the buffer layer 120 including the GaN layer and the energy band gap of the light absorption layer 130 including the GaN layer may be the same, and Al _k2 Ga ₁ the energy band gap of the capping layer 140 including the _{- k2} N (0 < k2 < 1) layer may be larger than the energy band gap of the light absorption layer 130.

Referring to FIG. 6A, the low-current blocking layer 125 has a structure in which Al _t Ga _{1 -t} N (0 <t <1) layers having different Al compositions are alternately stacked. When the Al composition of the low current blocking layer 125 is higher than that of the light absorbing layer 130 or when the Al composition of the low current blocking layer 125 is lower than that of the light absorbing layer 130, the cut off slope is changed . Referring to FIG. 6B, the low-current blocking layer 125 may be composed of a single layer Al _t Ga _{1 -t} N (0 <t <1). In this case, the energy band gap of the low-current blocking layer 125 may be larger than that of the light absorbing layer 130.

7 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention. The cross-sectional view of FIG. 7 is a cross-sectional view taken along the perforated line A-A 'of FIG. 1, with a difference that further includes an intermediate buffer layer 125' as compared to the cross-sectional view of FIG. Therefore, the detailed description of the same configuration will be omitted and the difference will be mainly described.

The intermediate buffer layer 125 'is grown between the light absorption layer 130 and the high temperature buffer layer 122 at a temperature higher than or equal to the growth temperature of the light absorption layer 130.

The light-absorbing layer _{(130) In y Ga 1 -} y N (0 <y <1) those containing layer, an intermediate buffer layer (125 ') are _{In z Ga 1-z N (} 0 <z <1) layer / GaN The layer may comprise a plurality of layers cross-laminated. When the intermediate buffer layer 125 'includes a plurality of layers, each layer may have the same thickness or different thicknesses from each other, and the thickness of each layer and the number of layers may be appropriately selected as needed . At this time, if the total thickness of the intermediate buffer layer 125 'is higher than the threshold thickness for lowering the crystallinity, the thickness of the intermediate buffer layer 125' may be limited because the efficiency of the light absorption layer may be lowered than the case where the intermediate buffer layer is not applied. The entire thickness of the intermediate buffer layer 125 'may be 50 nm or more to improve the crystallinity of the light absorbing layer 130.

For example, in the case of manufacturing a light receiving element for detecting ultraviolet light in the UVA region, the high-temperature buffer layer 122 is grown at a temperature of 1050 ° C., the growth temperature is lowered, the intermediate buffer layer 125 'is grown at about 900 ° C., The light absorbing layer 130 can be grown inside and outside. The intermediate buffer layer 125 'according to the present embodiment improves the photocurrent efficiency of the light absorption layer 130 by complementing the characteristic of the crystal generated when the light absorption layer 130 is grown at a lower temperature than the high temperature buffer layer 122 , It can be used as a role to adjust the cutoff slope in some cases.

8 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention. Specifically, Figure 8 shows the energy band diagram of the layer of the ultraviolet detecting element of Figure 7, wherein the light absorbing layer 130 is In _y Ga _{1 -} includes _{y N (0 <y <1} ) layer, a capping layer ( 140) is a GaN layer and / or Al _k3 Ga _{1 -} comprises _{k3 N (0 <k3 <1} ) layer.

8, the energy band gap of the contact layer 120 including the GaN layer is the same as the energy band gap of the intermediate buffer layer 125 having a structure in which the GaN layer / In _z Ga _{1 -z} N (0 <z <1) of greater than or equal to the energy band gap, in _y Ga _{1 - y} N energy band gap of the light absorbing layer 130 including the (0 <y <1) layer is equal to or smaller than the energy band gap of the intermediate buffer layer 125 . Also greater than the energy band gap of the GaN layer and / or _{Al k3 Ga 1 -k3 N (0} <k3 <1) the energy band gap of the capping layer 140 including a light absorbing layer (130).

9 is a sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention. 9 is a cross-sectional view taken along the percutaneous line A-A 'in FIG. 1, and has a difference that further includes the antistatic layer 123 as compared with the sectional view of FIG. Therefore, the detailed description of the same configuration will be omitted and the difference will be mainly described.

The antistatic layer 123 may comprise a GaN layer. An antistatic layer 123 may be formed on the second buffer layer 122 by forming a first electrode 170, for example, an n-type GaN layer, which is typically doped with Si, . That is, the ESD characteristic of the Schottky junction structure is lower than that of the PIN structure due to the Schottky junction structure structure. In the Schottky junction structure, the low current blocking layer 125 is grown for the improvement of electrostatic discharge (ESD) An antistatic layer 123 containing a GaN layer may be further grown to enhance the electrostatic discharge before Si is not arbitrarily doped. The antistatic layer 123 thus grown can improve the electrostatic discharge characteristics.

The capping layer 150, the light absorption layer 140 and the low-current blocking layer 130 as well as the antistatic layer 123 may be etched by dry etching or the like in order to form the second electrode 190 have. In this case, the second electrode 190 may be formed on the second buffer layer 122 exposed by etching.

10 shows an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention. Specifically, Figs. 10A and 10B show energy band diagrams of respective layers of the ultraviolet detecting element of Fig. 9, wherein the light absorbing layer 130 includes a layer of Al _x Ga _{1 -x} N ((0 <x <0.7) , The capping layer 140 includes Al _{k1Ga1 -k1N} (0 < k1 < 1) layer in which the composition of Al is higher than that of the light absorbing layer 130. [

10A and 10B, the energy band gap between the contact layer 120 and the antistatic layer 123 is the same. The energy band gap of the light absorption layer 130 is higher than the energy band gap of the contact layer 120 and the energy band gap of the capping layer 140 is higher than the energy band gap of the light absorption layer 130.

On the other hand, FIG. 10A shows a case where the low current blocking layer 125 is composed of Al _t Ga _{1 -t} N (0 <t <1) layers having different Al compositions, Off slope may be changed when the Al composition of the low-current blocking layer 125 is higher than that of the light absorption layer 130 or when the Al composition of the low-current blocking layer 125 is lower than that of the light absorption layer 130.

11 is a cross-sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention.

11, an ultraviolet ray detecting element according to the present embodiment is substantially similar to the ultraviolet ray detecting element according to the embodiment disclosed in FIG. 9 except that an AlN layer 124 is formed on the second buffer layer 122 . Hereinafter, description of the same configuration will be omitted and differences will be mainly described.

UV detection device according to this embodiment the second buffer layer 122 including a light absorbing layer 130, the light absorbing layer 130 is formed on the _{Al x Ga 1 - x N (} 0 <x <0.7) comprises a layer can do. The light absorbing layer 130 may have an Al content of 30% or more and a thickness of 0.1 占 퐉 or more for use as a specific ultraviolet region (for example, UVC) detecting absorbing layer.

Cracks may be generated due to a difference in lattice mismatching and thermal expansion coefficient between the light absorbing layer 130 and the second buffer layer 122 during growth under such conditions, .

Accordingly, the high-temperature AlN layer 124 having the same growth temperature as that of the light absorption layer 130, for example, about 1050, is formed between the second buffer layer 122 and the light absorption layer 140, and cracks can be suppressed.

 On the other hand, when the AlN layer 124 is used, cracking can be suppressed, but since the energy band gap of the AlN layer 124 is as large as about 6 eV, it is close to the insulating layer and it is difficult to obtain high- This can interfere with the flow of minute currents. Therefore, the thickness of the AlN layer 124 has a thickness of 100 nm or less.

Current blocking layer 125 according to the present embodiment is formed between the AlN layer 124 and the light absorbing layer 130 and is formed in the same light emitting layer 130 as the light absorbing layer 130 &Lt; / RTI &gt; At this time, the total thickness of the low-current blocking layer 125 may be set to 0.06 to 0.10 m in order to minimize a decrease in the current flow caused by the light energy absorbed in the light absorbing layer 130.

12 shows an energy band diagram according to another embodiment of the present invention. Specifically, Fig. 12 shows an energy band diagram of the ultraviolet detecting element of Fig.

More specifically, Figure 12a and 12b are _{Al x Ga 1 - x N (} 0 <x <0.7) not less than an Al composition of 30% of the light absorbing layer 130 including a layer, the light absorbing layer 130, a contact layer (120 The energy of the ultraviolet light emitting element having a structure in which the AlN layer 124 is interposed between the contact layer 120 and the low current blocking layer 125 is used to prevent cracks that may be generated when the AlN layer 124 is grown on the substrate Represents a band diagram. 12A and 12B, the energy band gap of the light absorption layer 130 is higher than the energy band gap of the contact layer 120 and the energy band gap of the capping layer 140 is higher than the energy band gap of the light absorption layer 130. [ And the energy band gap of the AlN layer 124 is higher than the energy band gap of the low current blocking layer or the capping layer.

12A shows a case where the low current blocking layer 125 is composed of Al _t Ga _{1 -t} N (0 <t <1) layers having different Al compositions, Off slope may be changed when the Al composition of the low-current blocking layer 125 is higher than that of the light absorption layer 130 or when the Al composition of the low-current blocking layer 125 is lower than that of the light absorption layer 130.

13 is a sectional view of an ultraviolet ray detecting element according to another embodiment of the present invention. 13 is a cross-sectional view taken along section line A-A 'in FIG. 1, with the difference that the capping layer 140 includes a first layer 141 and a second layer 142, as compared to the cross-sectional view of FIG. 7 . Therefore, the description of the same configuration will be omitted below, and the difference will be mainly described.

The light absorption layer 130 according to the present embodiment includes a layer of In _y Ga _{1 - y} N (0 <y <1). The capping layer 140 may include a first layer 141 and a second layer 142. The first layer 141 is grown on the light absorbing layer 130 comprising an In _y Ga _{1 -yN} (0 <y <1) layer. The first layer 141 may have a growth temperature equal to that of the light absorption layer 130 after growth of the light absorption layer 130 so as to prevent In from being decomposed during the growth of the light absorption layer 130 including In, For example, the GaN layer may be grown at 700 to 900 ° C. The second layer 142 is the Al _k3 Ga ₁ by supplying Al source on the first layer 141 _may be grown to _k3 N layer (0 <k3 <1). The second layer 142 is grown to include Al at a growth temperature higher than that of the light absorption layer 130, for example, 900 to 1000 ° C., so that the Schottky characteristic of the Schottky layer 150 can be easily obtained. It is also possible to laminate the first layer and the second layer each having a different composition.

The first layer 141 and the second layer 142 may each have a thickness, for example, 1 nm to 10 nm, at which a tunneling effect can occur. If the thicknesses of the first layer 141 and the second layer 142 are too large, proper thickness maintenance is required since the capping layer can act as a light absorbing layer.

14 is an energy band diagram of an ultraviolet detecting element according to another embodiment of the present invention.

14, an ultraviolet detecting element according to an embodiment of the present invention includes an intermediate buffer layer 125 'having a multi-layer structure having an energy band gap lower than that of the contact layer 120 on the contact layer 120, A light absorbing layer 130 having an energy band gap lower than or equal to that of the intermediate buffer layer 125 'is grown on the buffer layer 125' and a light absorbing layer 130 having a higher energy band gap than the light absorbing layer 130 is formed on the light absorbing layer 130. The capping layer of the first layer 141 and the capping layer of the second layer 142 having a higher energy band gap than the capping layer of the first layer 141 can be grown.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be.

That is, it should be understood that the embodiments described above are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

Accordingly, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100; Ultraviolet detection element
110; Board
120; Buffer layer
130; The light absorbing layer
140; The capping layer
150; Schottky layer
160; The insulating film layer
170; The first electrode layer
180; The second electrode layer

Claims (20)

Board;
A buffer layer located on the substrate;
A light absorbing layer disposed on the buffer layer;
A capping layer disposed on the light absorbing layer; And
And a Schottky layer located in a partial region on the capping layer,
Wherein the capping layer has a larger energy band gap than the light absorption layer. The method according to claim 1,
Wherein the light absorbing layer comprises a layer of Al _x Ga _{1 - x} N (0 < x < 0.7)
Wherein the capping layer comprises an AlGaN layer having a higher Al ratio than the light absorption layer. The method of claim 2,
Further comprising a low current blocking layer located between the buffer layer and the light absorbing layer,
Wherein the low current blocking layer comprises a single AlGaN layer or a plurality of AlGaN layers having different Al ratios. The method of claim 3,
Further comprising an antistatic layer positioned between the buffer layer and the low current blocking layer,
Wherein the antistatic layer comprises a GaN layer in which Si is not doped arbitrarily. The method of claim 3,
When the proportion of Al in the light absorbing layer is 30% or more,
And an AlN layer positioned between the buffer layer and the low current blocking layer. The method according to claim 1,
Wherein the light absorption layer comprises a GaN layer,
Wherein the capping layer comprises an AlGaN layer. The method of claim 6,
Further comprising a low current blocking layer located between the buffer layer and the light absorbing layer,
Wherein the low current blocking layer comprises a single AlGaN layer or a plurality of AlGaN layers having different Al ratios. The method according to claim 1,
Wherein the light absorption layer comprises a layer of In _y Ga _{1 - y} N (0 <y <1). The method of claim 8,
Wherein the capping layer comprises a GaN layer or an AlGaN layer. The method of claim 8,
Wherein the capping layer comprises a first layer covering the light absorbing layer and a second layer located on the first layer,
Wherein the first layer comprises a GaN layer and the second layer comprises an AlGaN layer. The method of claim 10,
Wherein the first layer and the second layer each have a thickness of 1 nm to 10 nm. The method of claim 8,
Further comprising an intermediate buffer layer positioned between the buffer layer and the light absorbing layer,
Wherein the intermediate buffer layer comprises a plurality of InGaN layers and a GaN layer. The method according to claim 1,
Wherein the light absorption layer is formed to a thickness of 0.05 탆 to 0.5 탆. The method according to claim 1,
Wherein the substrate is any one of a sapphire substrate, a SiC substrate, a GaN substrate, an AlN substrate, and a Si substrate. The method according to claim 1,
Wherein the buffer layer comprises a first buffer layer located on the substrate, and a second buffer layer located on the first buffer layer,
Wherein the first buffer layer and the second buffer layer each comprise a GaN layer. The method according to claim 1,
Wherein the Schottky layer is made of any one of ITO, Ni, ATO, Pt, W, Ti, Pd, Ru, Cr and Au. The method according to claim 1,
And an insulating film layer disposed on the capping layer, wherein the insulating film layer covers the upper surface and the side surface of the Schottky layer. 18. The method of claim 17,
Wherein the insulating film layer is any one of a SiNx layer and a SiOx layer. The method according to claim 1,
And a first electrode layer located on the Schottky layer. The method of claim 19,
And a second electrode layer disposed on the buffer layer,
And the second electrode layer is ohmic-bonded to the buffer layer.

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