A ternary alloy Lu x In 1-x Preparation of O material and its application in solar-blind ultraviolet detectors

Abstract

The present invention discloses the preparation of a ternary alloy LuxIn1-xO with adjustable bandgap and its application in solar-blind ultraviolet detectors. A preparation method of a ternary alloy LuxIn1-xO material with adjustable bandgap, which uses magnetron sputtering to prepare the ternary alloy LuxIn1-xO material, and indium oxide target and lutetium oxide target are selected; the sputtering power of the indium oxide target is 25 - 35 W, and the sputtering power of the lutetium oxide target is 30 - 150 W; Ar and O2 are introduced into the equipment cavity, and at room temperature, LuxIn1-xO is obtained on the substrate, where 0 < x < 1. The present invention uses magnetron co-sputtering to introduce Lu atoms into the lattice of In2O3, realizing the broadening of the bandgap of the ternary alloy LuxIn1-xO (0 < x < 1) in the solar-blind ultraviolet region. By adjusting the sputtering power of the lutetium oxide target, the bandgap of the ternary alloy LuxIn1-xO thin film can be continuously adjusted within the range of 3.85 to 5.2 eV. The Pt / Lu0.39In0.61O / GaN heterojunction device constructed based on the Lu0.39In0.61O thin film with a bandgap width of ~5.2 eV exhibits stable and reliable solar-blind ultraviolet detection performance.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic detection, and particularly to the preparation of a ternary alloy Lu x In 1-x O material and its application in a solar-blind ultraviolet detector. Background Art

[0002] Solar-blind ultraviolet detectors based on wide-bandgap semiconductors have significant advantages in terms of volume, reliability, and application flexibility, and have received extensive attention in fields such as short-range communication, flame detection, and ecological environment detection. To improve the spectral selectivity of detectors in the solar-blind ultraviolet band, it is generally required that the bandgap of the photosensitive layer semiconductor material for preparing the detector is greater than 4.2 eV. Semiconductors such as gallium oxide, diamond, and AlN are ideal candidate materials for preparing solar-blind ultraviolet detectors due to their intrinsically ultra-wide bandgap characteristics. However, the types of semiconductor materials with an intrinsic wide bandgap are limited, which will hinder the development of various types of solar-blind ultraviolet detectors.

[0003] Broadening the bandgap of narrow-bandgap semiconductor materials through bandgap engineering is a commonly used strategy to broaden the selection range of photosensitive layer materials for solar-blind ultraviolet detectors. For example, ternary alloy materials such as MgZnO and AlGaN that can achieve bandgap broadening through composition regulation have been reported for the preparation of high-performance solar-blind ultraviolet detectors. Achieving bandgap broadening of these traditional, crystalline-oriented ternary alloys often requires strict synthesis processes. Therefore, bandgap regulation of amorphous alloy materials with simple synthesis process characteristics has received significant attention in the field of bandgap engineering. Summary of the Invention

[0004] To overcome the above-mentioned deficiencies of the prior art, the present invention provides a method for preparing a ternary alloy Lu x In 1-x O material and its application in a solar-blind ultraviolet detector.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] In the first aspect of the present invention, a method for preparing a ternary alloy Lu x In 1-x O material is provided. The ternary alloy Lu x In 1-x O material is prepared by a magnetron sputtering method, and indium oxide target and lutetium oxide target are selected; the sputtering power of the indium oxide target is 25 - 35 W, and the sputtering power of the lutetium oxide target is 30 - 150 W; Ar and O2 are introduced into the equipment cavity, and at room temperature, Lu x In 1-x O is obtained on the substrate, where 0 < x < 1.

[0007] In2O3 is an n-type semiconductor material with a band gap width of about 3.6 - 3.75 eV and an electron mobility as high as 300 cm 2 ·V -1 ·s -1 . Lutetium oxide (Lu2O3), a super wide-bandgap semiconductor with a band gap width of 5.5 - 6.0 eV. In addition, the radii of Lu 3+ ions and In 3+ ions are close to each other, being and respectively. The bond lengths of Lu–O and In–O are 0.222 and 0.220 nm respectively. Therefore, at a high doping concentration, the influence of Lu doping on the lattice distortion of the In2O3 film is relatively small.

[0008] Preferably, the sputtering power of the indium oxide target is 30 W.

[0009] Preferably, the substrate is a sapphire substrate, and a GaN thin film is epitaxially grown on the sapphire substrate.

[0010] Preferably, 20 sccm Ar and 3 sccm O2 are introduced into the device cavity and the cavity pressure is maintained at 0.6 Pa.

[0011] Preferably, the band gap width of Lu x In 1-x O is 3.85 - 5.2 eV.

[0012] The second aspect of the present invention provides a band-gap tunable ternary alloy Lu x In 1-x O material prepared by the preparation method of the band-gap tunable ternary alloy Lu x In 1-x O material.

[0013] The third aspect of the present invention provides the application of the band-gap tunable ternary alloy Lu x In 1-x O material in the preparation of solar-blind ultraviolet detectors.

[0014] The fourth aspect of the present invention provides a solar-blind ultraviolet detector, the structure of which includes, from bottom to top in sequence:

[0015] A sapphire substrate; a GaN thin film is epitaxially grown on the sapphire substrate;

[0016] A ternary alloy thin film, the ternary alloy thin film is deposited on the surface of the sapphire substrate; the ternary alloy thin film is the band-gap tunable ternary alloy Lu x In 1-x O material;

[0017] The positive electrode of the solar-blind ultraviolet detector is Pt, and the negative electrode is In.

[0018] The positive electrode Pt of the solar-blind ultraviolet detector is deposited on the surface of the ternary alloy film by a sputtering method; the negative electrode In of the device is directly welded on the GaN substrate by an electric soldering iron.

[0019] Preferably, the ternary alloy film is Lu 0.39 In 0.61 O thin film; the Lu 0.39 In 0.61 The atomic molar composition ratio of Lu / In in the O film is (0.385-0.395):(0.605-0.615).

[0020] Preferably, the thickness of the ternary alloy film is 190-220 nm; the thickness of the GaN film is 800-1200 nm; further preferably, the thickness of the ternary alloy film is 200-210 nm; the thickness of the GaN film is 900-1000 nm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts the method of magnetron co-sputtering to introduce Lu atoms into the In2O3 lattice to achieve Lu x In 1-x O(0 <x<1)三元合金的带隙在日盲紫外区域的展宽。通过调节氧化镥靶材的溅射功率,可以实现Lu x In 1-x The band gap of the O ternary alloy film is continuously adjustable in the range of 3.85 to 5.2 eV. 0.39 In 0.61 Pt / Lu constructed by O thin film x In 1-x The O / GaN heterojunction device demonstrates stable and reliable solar-blind UV detection performance. Under 0V bias, the device's peak response is ~0.81mA / W (corresponding to a response band of 255nm), and the solar-blind UV-visible suppression ratio is (R 255nm / R 400nm )~318, decay time is ~0.56s. 0.39 In 0.61 O / GaN devices have larger short-circuit current, larger open-circuit voltage and smaller dark current density. The Schott junction at the interface between the Pt electrode and the film is Lu 0.39 In 0.61The important reason why the O / GaN heterojunction device exhibits reliable solar-blind ultraviolet optoelectronic performance under a 0 V bias. The present invention is of great significance for expanding the application of the Lu x In 1-x O ternary alloy in the field of solar-blind ultraviolet detection. Brief Description of the Drawings

[0023] Figure 1 The functional relationship between the absorption coefficient (α) and the band gap of the Lu x In 1-x O thin film with different Lu component dopings deposited on a sapphire substrate; hv is the photon energy;

[0024] Figure 2 For Lu 0.39 In 0.61 High-resolution XPS spectra of Lu, In, and O in the O thin film;

[0025] Figure 3 For Lu 0.39 In 0.61 Cross-sectional morphology of Lu

[0026] Figure 4 For Lu 0.39 In 0.61 SEM image of Lu

[0027] Figure 5 For Lu 0.39 In 0.61 XRD pattern of the Lu

[0028] Figure 6 For Pt / Lu 0.39 In 0.61 I-V (linear coordinates) of the O / GaN heterojunction device under dark conditions; the inset is a schematic diagram of the device prototype;

[0029] Figure 7 For electrode contact test: I-V curves between In / In and adjacent Pt / Pt;

[0030] Figure 8 I-V (logarithmic coordinates) of the device under dark and light conditions;

[0031] Figure 9 Spectrum of the device under a 0 V bias;

[0032] Figure 10 Optoelectronic performance of the device under a 0 V bias;

[0033] Figure 11 For Au / Lu 0.39 In 0.61 O / GaN device and Pt / Lu0.39 In 0.61 Performance comparison of O / GaN devices. Detailed implementation manners

[0034] The following further describes the detailed implementation manners of the present invention. It should be noted here that the description of these implementation manners is used to help understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the various implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] The experimental methods in the following examples are all conventional methods unless otherwise specified, and the test materials used in the following examples are all commercially available through conventional channels unless otherwise specified.

[0036] Example 1

[0037] This example provides a preparation method for a Lu x In 1-x O ternary alloy thin film and a solar-blind ultraviolet detector, which specifically include the following steps:

[0038] Use the magnetron sputtering method (Jinsheng Micro-Nano MSP-3220) to co-sputter an indium oxide ceramic target (purity 99.99%) and a lutetium oxide ceramic target (purity 99.5%) to grow a ternary alloy thin film. First, select a sapphire substrate, and the doping ratio of Lu component and In in the ternary alloy thin film is regulated by the sputtering power of the target. Among them, the sputtering power of the indium oxide target is maintained at 30 W, and the sputtering powers of the lutetium oxide targets are 0 W, 60 W, 90 W, 100 W, and 150 W in sequence. Then, introduce 20 sccm Ar and 3 sccm O2 into the equipment cavity and keep the cavity pressure at 0.6 Pa. Under room temperature conditions, a series of ternary alloy thin films with different Lu component dopings (Lu 0.12 In 0.88 O, Lu 0.22 In 0.78 O, Lu 0.32 In 0.68 O, Lu 0.39 In 0.61 O) are deposited on the sapphire and gallium nitride substrates.

[0039] Construct a Lu 0.39 In 0.61 O / GaN heterojunction solar-blind ultraviolet detector. The positive electrode of the detector is a super-thin Pt layer with a thickness of about 5 nm, which is deposited on the surface of the Lu 0.39 In 0.61 O thin film by sputtering. The negative electrode of the device is In, which is directly welded to the n-GaN substrate by an electric soldering iron.

[0040] The relationship between the bandgap width and the film absorption coefficient of the ternary alloy film deposited on the sapphire substrate is as Figure 1 shown. It can be clearly seen that as the sputtering power of lutetium oxide increases, the bandgap of the film increases, which means that Lu component doping can effectively broaden the bandgap of Lu x In 1-x O film. When the Lu / In atomic molar component ratio is about 0.39:0.61 ( Figure 2 high-resolution XPS spectra of Lu, In, and O elements in 0.39 In 0.61 O film), the bandgap of Lu 0.39 In 0.61 O film is about 5. eV, which can be used for solar-blind ultraviolet detectors. Lu Figure 3 ) The surface SEM image of the film is as Figure 4 shown. According to the EDS spectra (d1, d2, d3), it can be confirmed that Lu, In, and O elements are uniformly distributed in the film. No characteristic diffraction peaks other than the substrate were observed in the XRD pattern of the film ( Figure 5 ), indicating that the ternary film is an amorphous film. The synthesis process of the amorphous film of the present invention does not need to additionally consider the phase separation problem that may be caused by high-component element doping, and is a simple and easily repeatable material growth process.

[0041] Pt / Lu 0.39 In 0.61 O / GaN heterojunction device prototype schematic diagram is shown in the inset of Figure 6 . Under dark conditions, the device exhibits an obvious rectifying effect ( Figure 6 ). The excellent ohmic contact between the In electrode and GaN indicates that there is no contact barrier between the negative electrode and the substrate ( Figure 7 ). The linear I-V curve obtained by measuring two points on the Pt electrode with a distance of about 0.3 mm selected on the Pt electrode with an area of 1.35 mm 2 ( Figure 7 ) shows that the area of this conductive ultra-thin Pt layer is the effective irradiation area of the incident light in the device. In addition, under the reverse 1V bias condition, the photocurrent exhibited by the device is two orders of magnitude larger than the dark current exhibited by the device ( Figure 8 ), indicating that the device has a high sensitivity to the detection of solar-blind ultraviolet light signals. At the same time, when the device is under solar-blind ultraviolet irradiation conditions, an open-circuit voltage of about 0.36V is presented, verifying that the device can achieve solar-blind ultraviolet detection in a zero-power consumption mode. From Figure 9It can be obtained that the device achieved a peak response of ~0.81 mA / W under irradiation at a wavelength of 255 nm, and the device had a solar-blind ultraviolet-visible rejection ratio of ~318. This indicates that a Lu 0.39 In 0.61 O / GaN photovoltaic detector was successfully constructed.

[0042] The optoelectronic properties of the device under a 0 V bias are as Figure 10 shown, where (a) is the single-cycle I-T; (b) is the multi-cycle I-T; (c) is the single-cycle I-T under variable light rate conditions; (d) is the curve of the device decay time versus optical power; (e) is the I-V curve under variable power conditions; (f) is the curve of the open-circuit voltage and short-circuit current versus optical power. Under a single-cycle optical power of 9.91 μW and illumination at 254 nm, the decay time of the device was ~0.56 s ( Figure 10 a), and the decay time of the device was defined as the time taken for the current to change from 90% of the maximum value to 10% of the minimum value. When multi-cycle solar-blind ultraviolet light irradiation was used, the time-dependent photocurrent curve of the device was stable and repeatable ( Figure 10 b). At the same time, the dynamic switching ratio of the device was higher than 2 orders of magnitude. All these indicate that the device has fast and reliable solar-blind ultraviolet signal detection performance. In Figure 10 c, the saturation photocurrent of the device increased with the increase of optical power, which can be attributed to the formation of more photo-generated carriers. In addition, the decay time of the device decreased with the increase of optical power ( Figure 10 d). This can be attributed to the reduction of the carrier lifetime caused by the increase of photo-generated carriers under high optical power conditions. Based on the I-V curve of the device under variable power illumination conditions ( Figure 10 e), it can be obtained that both the open-circuit voltage and the short-circuit current showed a positive correlation with the optical power ( Figure 10 f). Among them, the exponential factor obtained by fitting the linear relationship between the short-circuit current and the optical power was close to the ideal exponential factor of 1. This implies that the device has stable and uniform output characteristics in the photovoltaic working mode.

[0043] Comparative Example 1

[0044] This comparative example constructed an Au / Lu 0.39 In 0.61 O / GaN device based on Example 1, and the difference from Example 1 was that Pt was replaced by Au.

[0045] The performance comparison between the Au / Lu 0.39 In 0.61 O / GaN device and the Pt / Lu 0.39 In 0.61 O / GaN device is as Figure 11 shown, where (a) is the Au / Lu0.39 In 0.61 O / GaN and Pt / Lu 0.39 In 0.61 Comparison of dark current density of O / GaN; (b) is the comparison of forward photocurrent density of two devices; highlighting the differences in short - circuit current and open - circuit voltage; (c) is the photocurrent distribution of 3×3 array elements under 0V bias; (d) is the photocurrent distribution of 3×3 array elements under - 1V bias.

[0046] Au / Lu 0.39 In 0.61 The O / GaN device exhibits a larger dark current ( Figure 11 (a)) and a smaller short - circuit current and a smaller open - circuit voltage under solar - blind ultraviolet illumination conditions ( Figure 11 (b)). This can be attributed to the formation of a smaller Schottky barrier between Au with a smaller work function and the photosensitive layer. The Schottky barrier formed between the electrode and the photosensitive layer plays a key role in the photovoltaic behavior that occurs in the Lu 0.39 In 0.61 O / GaN heterojunction. At the same time, whether under 0V bias or - 1V reverse bias ( Figure 11 (c), (d)), the photocurrent values of the 3*3 array - element devices on the same Pt / Lu 0.39 In 0.61 O / GaN planar array show good uniformity, which implies the uniformity of the quality of the Lu 0.39 In 0.61 O thin film.

[0047] In summary, by using the magnetron sputtering method, indium oxide and lutetium oxide are alloyed, and the band - gap width of the Lu x In 1-x O ternary alloy can be regulated in the solar - blind ultraviolet region. Based on the Lu 0.39 In 0.61 O thin film with a band - gap width of ∼5.2eV and GaN to construct the Pt / Lu 0.39 In 0.61 O / GaN device, under 0V bias, shows stable and reliable detection characteristics for solar - blind ultraviolet signals. The device has a peak responsivity of ∼0.81mA / W, a decay time of ∼0.56s, and an ultraviolet - visible rejection ratio of ∼318 at a wavelength of 253nm. Among them, the Schottky barrier formed between the Pt electrode and the photosensitive layer is an important inducement for the photovoltaic behavior of the device. This work has a reference role in promoting the application of band - gap engineering in solar - blind ultraviolet detection.

[0048] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations to these embodiments still fall within the protection scope of the present invention.

Claims

1. A ternary alloy Lu with adjustable bandgap x In 1-x The preparation method of O material is characterized in that: Preparation of ternary alloy Lu by magnetron sputtering x In 1-x O material, indium oxide target and lutetium oxide target are selected; the sputtering power of the indium oxide target is 25-35W, and the sputtering power of the lutetium oxide target is 30-150W; Ar and O2 are introduced into the equipment cavity, and Lu is obtained on the substrate under room temperature. x In 1-x O, where 0 <x<1。 2. The bandgap-adjustable ternary alloy Lu according to claim 1 x In 1-x The preparation method of O material is characterized in that: The sputtering power of the indium oxide target is 30W.

3. The bandgap-adjustable ternary alloy Lu according to claim 1 x In 1-x The preparation method of O material is characterized in that: The base is a sapphire substrate, and a GaN thin film is epitaxially grown on the sapphire substrate.

4. A ternary alloy Lu with adjustable bandgap according to any one of claims 1 to 3 x In 1-x O material preparation method prepared by the band gap adjustable ternary alloy Lu x In 1-x O material.

5. The bandgap-adjustable ternary alloy Lu according to claim 4 x In 1-x Application of O materials in the preparation of solar-blind ultraviolet detectors.

6. A solar-blind ultraviolet detector, characterized in that: Its structure includes the following arranged from bottom to top: A sapphire substrate; a GaN thin film is epitaxially grown on the sapphire substrate; The ternary alloy film is deposited on the surface of the sapphire substrate; the ternary alloy film is the bandgap adjustable ternary alloy Lu according to claim 4. x In 1-x O Materials; The positive electrode of the solar-blind ultraviolet detector is Pt, and the negative electrode is In.

7. The solar-blind ultraviolet detector according to claim 6, characterized in that: The ternary alloy film is Lu 0.39 In 0.61 O film.

8. The solar-blind ultraviolet detector according to claim 6, characterized in that: The thickness of the ternary alloy film is 190-220 nm; the thickness of the GaN film is 800-1200 nm.

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