The Preparation Method and Application of An Er Doped Ga2O3 Film

Abstract

The present invention discloses an Er doped Ga.sub.2O.sub.3 film, together with its preparation method and the application in the field of luminescence. The preparation method contains steps of: (1) the films are deposited by means of Radio-Frequency magnetron sputtering onto the heated substrates after the pre-sputtering for at least 5 minutes, selecting Er doped Ga.sub.2O.sub.3 target or Er and Ga.sub.2O.sub.3 targets, with the ambient of Ar and O.sub.2; (2) the films as prepared in step (1) are thermally treated at the temperature higher than 300° C. in the ambient of O.sub.2 or N.sub.2, in order to optically activate Er.sup.3+ and crystalize Ga.sub.2O.sub.3 hosts meanwhile, followed by natural cooling, obtaining the Er doped Ga.sub.2O.sub.3 films as described. The preparation technology of the present invention is simple, with a good process compatibility. It is believed that the present invention will be widely used in the field of silicon-based integrated light sources, semiconductor luminescence, optical communication, with broad application prospects.

Claims

1. A near infrared electroluminescent device based on the impact of hot-electrons, characterized in that the device uses Ga.sub.2O.sub.3: Er films, whose preparation method comprising the steps of: (1) in a vacuum chamber, introducing mixed gas of Ar and O.sub.2, using Radio-Frequency magnetron sputtering method to sputter the erbium-doped gallium oxide target or co-sputter the erbium target and the gallium oxide target, after sputtering a blacking plate for 5 minutes, then starting sputtering deposition an erbium-doped gallium oxide film on a heated substrate; the substrate being thermally oxidized n-type silicon; (2) under an atmosphere of oxygen or nitrogen, subjecting the erbium-doped gallium oxide film obtained in step (1) to a high temperature heat treatment above 300° C. to crystallize the gallium oxide while activating the erbium, and then naturally cooling down to obtain the erbium-doped gallium oxide film; wherein one side of the substrate of the erbium-doped gallium oxide film is deposited with a metal back electrode for connecting to the negative electrode of the power supply, and another side of the erbium-doped gallium oxide film is deposited with an indium tin oxide (ITO) transparent electrode for connecting to the positive electrode of the power supply; and wherein an onset voltage of the near-infrared electroluminescent device based on hot electron impact ionization is lower than 20 V.

2. The near-infrared electroluminescent device based on hot electron impact ionization according to claim 1, characterized in that: during the preparation method in step (1), the temperature of the substrate is higher than 100° C.; the vacuum degree is no more than 5×10.sup.−3 Pa; the ratio of the volume flow is 2:1˜2:40; during the sputtering, the Ga.sub.2O.sub.3: Er target is fed with the power of 10-190 W, the Er and Ga.sub.2O.sub.3 targets are fed with the power of 5-50 W and 50-190 W, respectively; the pressure of the sputtering chamber is 0.1-10 Pa; the sputtering lasts for 5-60 min.

3. The near-infrared electroluminescent device based on hot electron impact ionization according to claim 1, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within the Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

4. A near-infrared electroluminescent device based on the recombination of electrons and holes, characterized in that the device uses Ga.sub.2O.sub.3: Er films, whose preparation method comprises: (1) in a vacuum chamber, introducing mixed gas of Ar and O.sub.2, using Radio-Frequency magnetron sputtering method to sputter the erbium-doped gallium oxide target or co-sputter the erbium target and the gallium oxide target, after sputtering a blacking plate for 5 minutes, then starting sputtering deposition an erbium-doped gallium oxide film on a heated substrate; the substrate being p-type silicon; (2) under an atmosphere of oxygen or nitrogen, subjecting the erbium-doped gallium oxide film obtained in step (1) to a high temperature heat treatment above 300° C. to crystallize the gallium oxide while activating the erbium, and then naturally cooling down to obtain the erbium-doped gallium oxide film; wherein one side of the substrate of the erbium-doped gallium oxide film is deposited with a metal back electrode for connecting to the positive electrode of the power supply, and another side of the erbium-doped gallium oxide film is deposited with an indium tin oxide (ITO) transparent electrode for connecting to the negative electrode of the power supply; and wherein an onset voltage of the near-infrared electroluminescent device based on the recombination of electrons and holes is lower than 6 V.

5. The near-infrared electroluminescent device NIR EL LED based on the recombination of electrons and holes according to claim 4, characterizes in that: during the preparation method in step (1), the temperature of the substrate is higher than 100° C.; the vacuum degree is no more than 5×10.sup.−3 Pa; the ratio of the volume flow is 2:1˜2:40; during the sputtering, the Ga.sub.2O.sub.3: Er target is fed with the power of 10-190 W, the Er and Ga.sub.2O.sub.3 targets are fed with the power of 5-50 W and 50-190 W, respectively; the pressure of the sputtering chamber is 0.1-10 Pa; the sputtering lasts for 5-60 min.

6. The near-infrared electroluminescent device NIR EL LED based on the recombination of electrons and holes according to claim 4, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within the Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

7. A method of using Erbium-doped gallium oxide thin films in near infrared electroluminescent devices, wherein the Erbium-doped gallium oxide thin film is prepared by the following steps: (1) in a vacuum chamber, introducing mixed gas of Ar and O.sub.2, using Radio-Frequency magnetron sputtering method to sputter the erbium-doped gallium oxide target or co-sputter the erbium target and the gallium oxide target, after sputtering a blacking plate for 5 minutes, then starting sputtering deposition an erbium-doped gallium oxide film on a heated substrate; the substrate being p-type silicon; or thermally oxidized n-type silicon; (2) under an atmosphere of oxygen or nitrogen, subjecting the erbium-doped gallium oxide film obtained in step (1) to a high temperature heat treatment above 300° C. to crystallize the gallium oxide while activating the erbium, and then naturally cooling down to obtain the erbium-doped gallium oxide film.

8. The method according to claim 7, wherein during the preparation method in step (1), the temperature of the substrate is higher than 100° C.; the vacuum degree is no more than 5×10.sup.−3 Pa; the ratio of the volume flow is 2:1˜2:40; during the sputtering, the Ga.sub.2O.sub.3: Er target is fed with the power of 10-190 W, the Er and Ga.sub.2O.sub.3 targets are fed with the power of 5-50 W and 50-190 W, respectively; the pressure of the sputtering chamber is 0.1-10 Pa; the sputtering lasts for 5-60 min.

9. The method according to claim 7, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

10. The near-infrared electroluminescent device based on hot electron impact ionization according to claim 2, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within the Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

11. The near-infrared electroluminescent device NIR EL LED based on the recombination of electrons and holes according to claim 5, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within the Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

12. The method according to claim 8, characterized in that: Ga.sub.2O.sub.3: Er crystals are produced within Ga.sub.2O.sub.3: Er films, whose grain diameters are 10-100 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 depicts the structure of the 2 typical devices based on the recombination of electrons and holes (left side) and impact of hot-electrons (right side), respectively.

[0034] FIG. 2 exhibits the X-ray diffraction (XRD) patterns of the films after thermal treatment, where the corresponding crystal planes are labeled.

[0035] FIG. 3 shows the image of the film thermally treated at 700° C. in O.sub.2 for 2 hours, acquired by an atomic force microscope (AFM).

[0036] FIG. 4 displays the representative current-voltage (I-V) characteristic curves for the devices based on the recombination of electrons and holes (left side) and impact of hot-electrons (right side), respectively.

[0037] FIG. 5 presents the EL spectra of the devices based on the recombination of electrons and holes (left side) and impact of hot-electrons (right side), respectively. The condition of the current and voltage during the EL measurement is explained by the labels of the figure.

DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be elaborated further combined with the figures and specific embodiments. Take note that the embodiments are only applicable to the present invention, but not used to restrain the scope of the invention. Detailed operation methods of the specific conditions are not indicated in the following embodiments. Instead, conventional conditions or the ones recommended by manufacturers are preferable.

[0039] In this embodiment, the EL devices based on Er doped Ga.sub.2O.sub.3 films are fabricated by means of RF magnetron sputtering, selecting Czochralski (CZ) single side polished p-silicon wafers with the crystal orientation of (100), electrical resistivity of less than 0.01 Ω.Math.cm and CZ single side oxidized (SiO.sub.2 thickness of ˜20 nm) n-silicon wafers with the crystal orientation of (100), electrical resistivity of less than 0.01 Ω.Math.cm as the substrates. During sputtering, the substrates are heated up to 150° C., and the chamber evacuated to the vacuum degree of 5×10.sup.−3 Pa in advance is inlet with the mixture gas of pure Ar and O.sub.2 to the pressure of 1 Pa, with the gas entry rate of 7.5:32.5. The Ga.sub.2O.sub.3 target doped with erbium-gallium molar ratio of 2:98 is used, fed with the power of 120 W. After pre-sputtering for 5 minutes, the baffles are removed and the formal sputtering lasts for 35 minutes. The as sputtered films are thermally treated in the ambient of O.sub.2 at 700° C. for 2 hours, heated and cooled down along with the furnace. Subsequently, the Au and Al electrodes are direct current (DC) sputtered onto one side of the p-Si and thermally oxidized n-Si, respectively, forming the Ohmic contact. Finally, ITO transparent electrodes are sputtered onto another side of the films, leading to the LED devices depicted in FIG. 1. The thicknesses of the ITO layer, the Ga.sub.2O.sub.3: Er layer, the Au and Al electrodes are about 100 nm.

[0040] The detailed preparation methods are as follows:

[0041] (1) For the p-Si wafers, standard RCA cleaning is firstly carried out, then diluted HF is used to eliminate the oxidization layer on the surface of the wafers. For the thermally oxidized n-Si, N.sub.2 is directly used to remove the dust. Subsequently, the wafers are moved into the chamber of the RF sputtering device, which will be evacuated to the vacuum degree of 2×10.sup.×3 Pa later. Meanwhile, the substrate is heated up to 150° C. After that, the chamber is inlet with pure O.sub.2 and Ar (the entry rate of the O.sub.2 and Ar are 7.5 mL/min and 32.5 mL/min, respectively) to the working pressure of 1 Pa. The Ga.sub.2O.sub.3: Er target with erbium-gallium molar ratio of 2:98 is selected. Finally, after the pre-sputtering of 5 minutes, the baffles are moved and the Ga.sub.2O.sub.3: Er films are deposited on the substrates.

[0042] (2) The films as prepared above are thermally treated in the ambient of pure O.sub.2 using the vacuum tube furnace at 700° C. for 2 hours, cooled down with the furnace subsequently, in order to make Er.sup.3+ distribute evenly and crystalize the Ga.sub.2O.sub.3 hosts. It can be indicated that crystals of Ga.sub.2O.sub.3 are produced within the films from FIGS. 2 and 3, with the diameter of 50 nm.

[0043] (3) Diluted HF is coated onto the back side of the treated samples to eliminate the surface oxidization layer. Later, the samples are moved into the chamber of the DC magnetron sputtering, which is evacuated to the vacuum degree of 5×10.sup.−3 Pa and then inlet with pure Ar to the pressure of 5 Pa. Metal electrodes are deposited onto the backside of the samples which are heated up to 150° C. via high purity Au or Al targets.

[0044] (4) The samples are moved into the chamber of the DC magnetron sputtering, evacuated to the vacuum degree of 5×10.sup.×3 Pa and inlet with pure Ar to the pressure of 0.2 Pa. ITO transparent electrodes are deposited onto the front side of the samples which are heated up to 150° C. via ITO targets.

[0045] (5) DC voltage is applied to the as-prepared devices for I-V measurements, as exhibited in FIG. 4. It can be demonstrated that the onset voltages of the devices based on p-Si and thermally oxidized n-Si are less than 6 V and 20 V, respectively. For the devices based on thermally oxidized n-Si, the current density of the device is relatively low, leading to the high efficiency, especially the external quantum efficiency.

[0046] (6) EL measurements are carried out for the as-prepared devices, as shown in FIG. 5, where sharp emission peaks located at ˜1540 nm can be clearly observed for both devices. Lower working voltage can be acquired for the devices based on p-Si, while the current the devices based on n-Si is lower, with a higher external quantum efficiency instead.

[0047] Additionally, various modifications or alternatives made by those skilled in the art after reading the descriptions above are also involved in the scope of this application.