JP5134262B2 - Luminescent body and manufacturing method thereof - Google Patents

Description

  The present invention relates to a light emitter having a wide emission spectrum width and a method for producing the same.

  In a white light source, white light is obtained by exciting a white phosphor with ultraviolet light. A conventional white phosphor used for such a white light source has a bright line in its emission spectrum, and color rendering under a white light source using the white phosphor is not always sufficient. .

However, in recent years, it has been known that white light emission having no bright line is observed by embedding carbon (C) in silicon oxide (SiO ₂ ) (see, for example, Non-Patent Document 1). Therefore, in order to obtain a white light emitter that does not include an emission line in the emission spectrum, it has been proposed to create a white light emitter in which carbon is embedded in silicon oxide by various methods. For example, Patent Document 1 proposes producing a white light emitting material by heat-treating fumed silica whose surface is modified with a hydrocarbon group. In Non-Patent Document 4, it is proposed to produce a white light emitter in which carbon is embedded in silicon oxide by performing carbon implantation on silicon oxide.

International Publication No. 2006/025428 Pamphlet S. Hayashi, M. Kataoka and K. Yamamoto, Japanese Journal of Applied Physics, Vol. 32 (1993), L273-L276 Y.H.Yu, S.P.Wong and I.H.Wilson, Physica Status Solidi (a), Vol. 168 (1998), p.531-534 J.Zhao, D.S.Mao, Z.X.Lin, B.Y.Jiang, Y.H.Yu, X.H.Liu, H.Z.Wang and G.Q.Yang, Applied Physics Letters, Vol. 73 (1998), p.1838-1840 J.Zhao, D.S.Mao, Z.X.Lin, B.Y.Jiang, Y.H.Yu, X.H.Liu and G.Q.Wang, Materials Letters, Vol. 38 (1999), p.321-325 T. Uchino and T. Yamada, Applied Physics Letters, Vol. 85 (2004), pp. 1164-1166

  However, with these white light-emitting body preparation methods, it has been difficult to obtain a white light-emitting body having sufficient light emission intensity for use as a light-emitting body for a white light source. This problem is common not only when creating a white illuminant, but generally when creating an illuminant with a wide emission spectrum width.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a light emitter having a high emission intensity and a wide emission spectrum width.

In order to achieve at least a part of the above object, the phosphor manufacturing method of the present invention includes (a) a step of preparing porous silicon, and (b) a carbon cluster in pores formed in the porous silicon. And (c) selectively oxidizing the silicon of the porous silicon on which the carbon clusters are formed, and the step (b) includes the step of forming the gas in a gas atmosphere containing hydrocarbons. It includes a step of heat-treating porous silicon .

  According to this method, after carbon clusters are formed in pores of porous silicon having a large surface area per unit volume, the silicon of porous silicon is selectively oxidized. As a result, the carbon clusters are embedded in the silicon oxide while maintaining the shape dispersed in the pores of the porous silicon. Therefore, since the area per unit volume of the interface between the carbon cluster and silicon oxide that is considered to contribute to light emission can be widened, a light emitter having a high light emission intensity and a wide light emission spectrum width can be manufactured.

  The light emitting body manufacturing method may further include (d) a step of heat-treating the porous silicon in which the silicon is selectively oxidized.

  According to this method, it is possible to further increase the emission intensity of the light emitter having a wide emission spectrum width.

  Note that the present invention can be realized in various modes. For example, it is realizable with aspects, such as a light-emitting body, its manufacturing method, the light-emitting body manufactured with the manufacturing method, a light source using these light-emitting bodies, and a light-emitting device.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Light emitter manufacturing equipment:
B. First Embodiment C. Example of the first embodiment:
D. Sample evaluation of the first embodiment:
E. Second embodiment:
F. Example of the second embodiment:
G. Sample evaluation of the second embodiment:

A. Light emitter manufacturing equipment:
FIG. 1 is a schematic configuration diagram showing a schematic configuration of the light emitter manufacturing apparatus 10. The luminous body manufacturing apparatus 10 includes a heat treatment furnace 100 and four gas supply units 200, 300, 400, and 500 that supply four kinds of gases to the heat treatment furnace 100.

  The heat treatment furnace 100 includes a chamber 110, two flanges 120 and 130, a heater 140, and a temperature controller 150. The chamber 110 is a tubular member made of quartz glass. A sample SMP is disposed at the center of the chamber 110. Flange 120 and 130 are attached to both ends of the chamber 110. Gas supply units 200 to 400 are connected to one flange 120 via a pipe 122. A pipe 132 for releasing the gas that has passed through the chamber 110 to the outside is connected to the other flange 130. The gas sent from the chamber 110 to the pipe 132 is released into the atmosphere after taking safety measures. Thereby, the pressure in the chamber 110 is maintained at substantially atmospheric pressure.

  A heater 140 is attached to the center of the chamber 110 so as to surround the outer periphery of the chamber 110. A thermocouple 142 is provided at a position in contact with the chamber 110 of the heater 140. The heater 140 and the thermocouple 142 are connected to the temperature controller 150. The temperature controller 150 controls the current value supplied to the heater 140 based on the output signal of the thermocouple 142. As a result, the temperature of the heater 140 near the thermocouple 142 is adjusted to a temperature set in advance in the temperature controller 150. By adjusting the temperature of the heater 140, the sample SMP disposed at the center of the chamber 110 is heated to almost the set temperature (that is, the temperature of the thermocouple 142). Therefore, hereinafter, the temperature measured by the thermocouple 142 is also referred to as “temperature of the heat treatment furnace 100”.

The first gas supply unit 200 includes an on-off valve 210 and a flow rate adjustment valve 220. Acetylene (C ₂ H ₂ ) is supplied to the on-off valve 210 via the pipe 202. The on-off valve 210 and the flow control valve 220 are connected by a pipe 212, and the flow control valve 220 and the pipe 122 are connected by a pipe 222. By opening the on-off valve 210, acetylene is supplied to the chamber 110 via the flow rate adjustment valve 220. At this time, the flow rate of acetylene supplied to the chamber 110 is set according to the opening degree of the flow rate adjustment valve 220.

The second gas supply unit 300 and the third gas supply unit 400 have the same configuration as that of the first gas supply unit 200. Nitrogen (N ₂ ) is supplied to the second gas supply unit 300. The nitrogen supplied to the second gas supply unit 300 is supplied to the chamber 110 with the flow rate adjusted by the flow rate adjustment valve 320 by opening the on-off valve 310. The third gas supply unit 400 is supplied with oxygen (O ₂ ). The oxygen supplied to the third gas supply unit 400 is supplied to the chamber 110 with the flow rate adjusted by the flow rate adjustment valve 420 by opening the on-off valve 410.

The fourth gas supply unit 500 includes three on-off valves 530 to 550 and a bubbler 560 in which water (H ₂ O) is stored, in addition to the on-off valve 510 and the flow rate adjustment valve 520. Argon (Ar) is supplied to the on-off valve 510 via the pipe 502. The flow control valve 520 and the on-off valve 530 are connected by a branch pipe 522. The on-off valve 530 and the pipe 122 are connected by a branch pipe 532. A branch pipe 522 on the upstream side of the on-off valve 530 is connected to a pipe 542 having an opening below the water surface of the bubbler 560 via the on-off valve 540. A branch pipe 532 on the downstream side of the on-off valve 530 is connected to a pipe 552 having an opening on the water surface of the bubbler 560 via the on-off valve 550.

  In the fourth gas supply unit 500, the on-off valve 510 and the on-off valve 530 are opened, and the on-off valves 540 and 550 are closed, so that the argon supplied to the fourth gas supply unit 500 can be adjusted in flow rate. The flow rate is adjusted by the valve 520 and supplied to the chamber 110. On the other hand, the flow rate of the argon supplied to the fourth gas supply unit 500 was adjusted by the flow rate control valve 520 by opening the open / close valve 510 and the open / close valves 540 and 550 and closing the open / close valve 530. After that, it passes through the bubbler 560. As the argon passes through the bubbler 560, the argon is wetted by the water stored in the bubbler 560. The amount of water vapor contained in the wet argon is adjusted by the water temperature in the bubbler 560.

B. First embodiment:
FIG. 2 is a flowchart showing a manufacturing process of the light emitter in the first embodiment. FIG. 3 is a schematic diagram schematically showing the state of the sample in the manufacturing process of the light emitter shown in FIG.

  In step S10, porous silicon (porous silicon) serving as a starting material for the light emitter is prepared. As shown in FIG. 3A, the prepared porous silicon 600 has a porous layer 610 and a substrate 620. A large number of pores 612 continuous from the surface are formed in the porous layer 610, and silicon (Si) of the porous layer 610 is microcrystallized into microcrystalline silicon 614. Such porous silicon 600 is formed by, for example, anodizing a p-type silicon single crystal substrate. However, as the porous silicon, those formed by other methods can be used as long as they have pores continuous from the surface having a pore diameter of 2 to 50 nm. For example, porous silicon formed from polycrystalline silicon can be used. For the formation of porous silicon from polycrystalline silicon, see "Variation of Photoluminescence Properties of Stain-Etched Si with Crystallinity of Starting Polycrystalline Si Films" (K. Haga et al., Journal of Applied Physics, Vol. 33 (1994). pp. L1733-L1736) and "Study of luminescent porous polycrystallin silicon thin films" (PGHan et al., Journal of Vacuum Science and Technology B, Vol. 14 (1996), pp. 824-826). is there. In addition, it is more preferable to use what has a pore with a hole diameter of 5-20 nm as porous silicon.

In step S20 of FIG. 2, carbonization is performed on the porous silicon prepared in step S10. Specifically, porous silicon is disposed in the center of the chamber 110 of the heat treatment furnace 100 (FIG. 1), and the temperature of the heat treatment furnace 100 is raised to the carbonization temperature while supplying nitrogen to the chamber 110. Then, after the temperature of the heat treatment furnace 100 reaches the carbonization temperature, after waiting for a predetermined time so that the temperature of the sample SMP (porous silicon) becomes substantially the carbonization temperature, supply of acetylene to the chamber 110 is started. To do. After the carbonization time has elapsed from the start of the supply of acetylene, the supply of acetylene is stopped and the temperature of the heat treatment furnace 100 is started to be lowered. In the first embodiment, the carbonization treatment is performed in a mixed gas atmosphere of acetylene and nitrogen. However, in general, the carbonization treatment can be performed in a mixed gas atmosphere of hydrocarbon and inert gas. is there. As the hydrocarbon, methane (CH ₄ ), ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ), acetylene (C ₂ H ₂ ), and the like can be used. However, it is more preferable to use acetylene as the hydrocarbon. Nitrogen, helium (He), argon, etc. can be used as the inert gas.

  The carbonization temperature can be appropriately set in the range of 400 to 1000 ° C, but is more preferably set in the range of 500 to 900 ° C. The volume ratio of the inert gas to the hydrocarbon in the mixed gas can be 4: 1 to 1: 2, more preferably 3: 1 to 1: 1, and 2: 1 to 1 :. More preferably, it is 1. The carbonization time is appropriately set between 15 minutes and 1 hour depending on the volume ratio of the inert gas to the hydrocarbon in the mixed gas, the carbonization temperature, and the like. By the carbonization process in step S20, as shown in FIG. 3B, carbon clusters (carbon clusters) 630 are formed in the pores 612 of the porous silicon 600.

  In step S30 of FIG. 2, a selective oxidation process for selectively oxidizing silicon is performed on the porous silicon that has been carbonized in step S20. Specifically, the porous silicon that has been carbonized is placed in the center of the chamber 110 of the heat treatment furnace 100 (FIG. 1). Then, the heat treatment furnace 100 is heated to the oxidation treatment temperature while supplying wet argon passed through the bubbler 560 (FIG. 1) to the chamber 110. After the sample SMP (porous silicon that has been carbonized) reaches substantially the oxidation treatment temperature and the oxidation treatment time has elapsed, the temperature reduction of the heat treatment furnace 100 is started. In the first embodiment, the selective oxidation treatment is performed in a wet argon atmosphere, but in general, the selective oxidation treatment can be performed in a wet inert gas atmosphere. Similar to the carbonization treatment, nitrogen, helium, argon, or the like can be used as the inert gas. In this way, in the selective oxidation process in step S30, since the oxidation process is performed with a wet inert gas, the selective oxidation process can also be referred to as a “wet oxidation process”. However, other methods can be used as long as silicon can be selectively oxidized by a method different from the wet oxidation treatment.

  The oxidation treatment temperature can be appropriately set in the range of 500 to 1000 ° C, but is more preferably set in the range of 600 to 900 ° C. The temperature of the bubbler 560 is normal temperature (about 25 ° C.) in order to suppress condensation in the pipes 552, 532, and 122 connecting the bubbler 560 and the chamber 110 and to increase the amount of water vapor in the inert gas. Set to However, for example, if dew condensation in the pipes 552, 532, and 122 can be suppressed by heating the pipes 552, 532, and 122, the temperature of the bubbler 560 can be made higher than room temperature. The time for the selective oxidation treatment is appropriately changed between 5 minutes and 6 hours depending on the amount of water vapor in the inert gas, the oxidation treatment temperature, and the like. However, the selective oxidation treatment time is more preferably 10 minutes to 5 hours, and still more preferably 30 minutes to 4 hours.

By the selective oxidation process in step S30, the microcrystalline silicon 614 of the porous layer 610 is oxidized as shown in FIG. 3C, and a silicon oxide layer 640 containing porous silicon oxide (SiO ₂ ) 642 is formed. Is done. In the silicon oxide 642, the carbon clusters 630 formed in the pores 612 remain without being oxidized, and the carbon clusters 630 continuous from the surface are embedded. Note that oxidation of the substrate 620 also proceeds at the interface between the silicon oxide layer 640 and the substrate 620. Therefore, silicon oxide at the interface between the silicon oxide layer 640 and the substrate 620 is formed by oxidation of the substrate 620.

C. Example of the first embodiment:
[Create sample]
In the example of the first embodiment, first, a p-type silicon single crystal substrate having a specific resistance of 0.015 to 0.025 Ω · cm was prepared. The prepared silicon single crystal substrate was anodized in a solution in which 40% hydrofluoric acid (HF) and ethanol were mixed at a ratio of 1: 1. The anodizing treatment was performed for 8 minutes in the dark. By controlling the current density during the anodic oxidation treatment, two types of porous silicon having different porosities were obtained from the prepared silicon single crystal substrate. The state of these porous silicon was evaluated with a transmission electron microscope (TEM). The pore diameter of porous silicon having a high porosity was about 15 to 20 nm. The pore diameter of the porous silicon having a low porosity was about 5 to 10 nm. The thickness of the porous layer was about 2.5 μm for both of the two polycrystalline silicons. Of the obtained two types of porous silicon, a part of porous silicon having a high porosity was extracted as a sample.

  Next, carbonization was performed on the two types of porous silicon obtained. The carbonization process was performed for 30 minutes by supplying 1.5 liters of nitrogen and 1 liter of acetylene per minute to the chamber 110 (FIG. 1). The carbonization temperature was three conditions of 650 ° C., 850 ° C. and 1000 ° C. When the temperature of the carbonization treatment was raised and lowered, 1.5 l of nitrogen was supplied to the chamber 110 per minute. A part of the porous silicon after carbonization was extracted as a sample.

Next, selective oxidation treatment was performed on the porous silicon that had been carbonized. The selective oxidation treatment was performed for 3 hours by supplying argon (Ar + H ₂ O) that had been wetted by passing the bubbler 560 through the chamber 110 at a flow rate of 0.9 l / min. The oxidation treatment temperature was three conditions of 650 ° C., 800 ° C., and 950 ° C. At the time of temperature increase and temperature decrease in the selective oxidation treatment, 0.9 l of dry argon was supplied to the chamber 110 per minute.

As a comparative example, oxidation treatment was performed on porous silicon that had been carbonized by a method different from that of the first embodiment. The oxidation process was performed by supplying a dry argon / oxygen mixed gas (Ar + O ₂ ) in place of the wet argon supplied to the chamber 110 in the selective oxidation process of step S30 (FIG. 2). Other procedures were the same as those in the selective oxidation process in step S30. The oxidation treatment was performed for 3 hours by supplying 0.9 l of argon and 0.3 l of oxygen per minute to the chamber 110. The oxidation treatment temperature was three conditions of 650 ° C., 800 ° C., and 950 ° C. Note that this oxidation treatment is performed in a dry gas atmosphere, so it can also be referred to as “dry oxidation treatment”.

Of the samples obtained in this way, the samples showing the evaluation results below are shown in the following table. In the following, the evaluated samples are referred to using the sample numbers (# 1 to # 16).

D. Sample evaluation of the first embodiment:
[Observation with electron microscope]
The state of the porous layer 610 (FIG. 3) before and after the selective oxidation treatment was observed with a transmission electron microscope. FIG. 4 is an explanatory view showing the result of observation with a transmission electron microscope of the sample before and after the selective oxidation treatment. FIG. 4A shows an observation result of the sample (# 2) in a state in which carbonization treatment is performed at 1000 ° C. on porous silicon having a high porosity. FIG. 4B shows an observation result of the sample (# 4) in a state where the selective oxidation treatment is performed at 800 ° C. on the sample formed under the same conditions as in FIG. 4 (a) and 4 (b) show a transmission electron microscope cross-sectional image (hereinafter also referred to as “cross-sectional image”) of each sample, an oxidation including a porous layer 610 (FIG. 3) and carbon clusters 630. An electron beam diffraction image (upper left part) of the silicon layer 640 (FIG. 3) is shown.

  In the cross-sectional image before the selective oxidation treatment in FIG. 4A, the porous structure extending from the surface of the porous silicon toward the inside was clearly observed. Further, from the electron beam diffraction image, it was found that the porous silicon was a crystal having the same orientation relationship as that of the substrate. On the other hand, it was found from the electron diffraction image of FIG. 4B that the porous silicon was made amorphous by oxidation. However, the porous structure was observed even after the selective oxidation treatment, although it collapsed as compared with that before the selective oxidation treatment.

[Evaluation of silicon state by Raman scattering]
5 and 6 are graphs showing the results of evaluating the state of silicon using Raman scattering. The silicon state was evaluated by irradiating the sample with an argon laser beam having a wavelength of 514 nm and measuring the Raman spectrum of the backscattered light from the sample. The horizontal axis of FIG. 5 and FIG. 6 represents the Raman shift. The vertical axis represents the intensity of the backscattered light (signal intensity). The signal intensity is an arbitrary unit (AU). The Raman spectrum was measured using porous silicon with high porosity (sample # 1) that was not carbonized or selectively oxidized, and porous silicon with high porosity that was carbonized at 1000 ° C. (sample # 1). It carried out about sample # 2- # 8).

  The graph of FIG. 5 shows high porosity porous silicon (sample # 1) that was not carbonized or selectively oxidized and high porosity porous silicon that was only carbonized at 1000 ° C. The Raman spectrum of (Sample # 2) is shown.

As shown in the graph of FIG. 5, the spectrum of the sample (# 1) that has not been carbonized or oxidized has a wave number of 500 cm derived from microcrystalline silicon in the porous silicon 600 (FIG. 3). and nearby peaks ^-1, and the peak near the wave number 520 cm ^-1 derived from the substrate 620, the two peaks were observed. On the other hand, the peak of the substrate 620 was not observed in the spectrum of the sample (# 2) subjected to only carbonization treatment at 1000 ° C. This is considered to be because the carbon cluster 630 was formed inside the pores 612 of the porous layer 610 by performing the carbonization treatment, so that the laser beam did not reach the substrate 620.

  The graph of FIG. 6 shows a Raman spectrum of a sample obtained by subjecting high porosity porous silicon subjected to carbonization treatment at 1000 ° C. to oxidation treatment under four different conditions. The upper two spectra show the Raman spectra of the samples (# 6, # 3) subjected to the oxidation treatment at 650 ° C. The lower two spectra show the Raman spectra of the samples (# 7, # 4) subjected to the oxidation treatment at 800 ° C.

  As can be seen from the graph of FIG. 6, the shape of the Raman spectrum of the sample (# 6) subjected to the dry oxidation at 650 ° C. and the sample (# 3) subjected to the wet oxidation at 650 ° C. Was almost the same as the Raman spectrum before the oxidation treatment (# 2 in FIG. 5).

  In the sample (# 7) subjected to the dry oxidation treatment at 800 ° C., the peak of microcrystalline silicon was not significantly changed compared to that before the oxidation treatment, but the peak of the substrate was observed. In contrast, in the sample (# 4) subjected to the wet oxidation treatment at 800 ° C., the microcrystalline silicon peak disappeared and only the substrate peak was observed. From this result, it is determined that most of the microcrystalline silicon 614 in the porous silicon 600 (FIG. 3) is oxidized to become transparent silicon oxide 642 by the wet oxidation treatment at 800 ° C. Although not shown in the graph, in the samples (# 5, # 8) subjected to the oxidation treatment at 950 ° C., the microcrystalline silicon is similar to the sample (# 4) subjected to the wet oxidation treatment at 800 ° C. No peak was observed. From this, it was found that at an oxidation treatment temperature of at least 800 ° C., the oxidation rate of microcrystalline silicon by the wet oxidation treatment is higher than the oxidation rate of microcrystalline silicon by the dry oxidation treatment.

[Evaluation of carbon cluster state by Raman scattering]
FIG. 7 is a graph showing the results of evaluating the state of carbon clusters using Raman scattering. Evaluation of the state of the carbon cluster was performed by irradiating the sample with an argon laser beam having a wavelength of 514 nm and measuring the Raman spectrum of the backscattered light from the sample, in the same manner as the evaluation of the state of silicon. The horizontal axis in FIG. 7 represents the Raman shift, and the vertical axis represents the signal intensity. The signal intensity is an arbitrary unit (AU). The measurement of the Raman spectrum was performed on porous silicon (samples # 2 to # 8) having a high porosity that was carbonized at 1000 ° C.

As shown in the graph of FIG. 7, the sample (# 2) not subjected to oxidation treatment, a peak was observed at a wavenumber of 1370 cm ^-1 and a wavenumber 1590 cm ^-1. These peaks are peaks derived from carbon called D-band and G-band. Similarly, D-band and G-band peaks were also observed in the sample (# 3) subjected to wet oxidation at 650 ° C. In the sample (# 4) subjected to the wet oxidation treatment at 800 ° C., the D-band and G-band peaks are not subjected to the oxidation treatment (# 2), and the sample subjected to the wet oxidation treatment at 650 ° C. All of these peaks are observed, although lower than (# 3). In contrast, in the sample (# 6) subjected to the dry oxidation treatment at 650 ° C., neither the D-band nor the G-band peak was observed. Further, although not shown in the graph, the sample (# 5) subjected to the wet oxidation treatment at 950 ° C. and the sample (# 7, # 8) subjected to the dry oxidation treatment at 800 ° C. and 950 ° C. are also 650 Similar to the sample (# 6) subjected to the dry oxidation treatment at 0 ° C., neither the D-band nor the G-band peak was observed. From this, it was found that the carbon cluster 630 formed in the pores 612 of the porous silicon 600 (FIG. 3) is oxidized by performing the dry oxidation treatment. Further, it has been found that the carbon cluster 630 is oxidized by wet oxidation at an oxidation temperature of 950 ° C. or higher.

  From the above evaluation results of the states of silicon and carbon clusters, the oxidation of the carbon clusters 630 (FIG. 3) is suppressed by performing wet oxidation treatment at an oxidation treatment temperature of at least 800 ° C. It was found that the microcrystalline silicon 614 included in the film is selectively oxidized.

[Evaluation of photoluminescence]
8 to 12 are graphs showing the evaluation results of photoluminescence. The horizontal axis of these graphs represents the wavelength, and the vertical axis represents the emission intensity. The emission intensity is in arbitrary units (AU). Photoluminescence was evaluated by exciting the sample with an argon laser beam having a wavelength of 351 nm and measuring the emission spectrum from the sample. The intensity of the argon laser light (excitation light) was 2 mW.

  First, the photoluminescence intensity of porous silicon that was not carbonized (sample # 1) and samples that were carbonized at 1000 ° C. (# 2 to # 8) were evaluated. FIG. 8 is a graph showing an emission spectrum of samples (# 1, # 3, # 4) in which photoluminescence is observed among these samples (# 1 to # 8). In the graph of FIG. 8, the spectrum of the sample subjected to carbonization treatment and wet oxidation treatment is indicated by a solid line, and the spectrum of the sample not subjected to carbonization treatment is indicated by a broken line.

  As shown in the graph of FIG. 8, red light having a peak wavelength of about 700 nm was observed in the porous silicon (sample # 1) that was not carbonized as in the case of typical porous silicon. Note that the vibration of the spectrum of sample # 1 indicates interference in the porous layer 610 (FIG. 3). Also, the vibrations observed in other spectra indicate interference at the silicon oxide layer 640 (FIG. 3). On the other hand, no photoluminescence was observed in the porous silicon (# 2) subjected to carbonization only. In addition, no photoluminescence was observed in the samples (# 6 to # 8) subjected to the dry oxidation treatment in which the carbon clusters were considered to be oxidized as described above and the samples subjected to the wet oxidation treatment at 950 ° C.

  In the sample (# 3) subjected to the wet oxidation treatment at 650 ° C., although the emission intensity was low, emission with a broad spectrum width having a peak wavelength of about 500 nm was observed. In the sample (# 4) subjected to the wet oxidation treatment at 800 ° C., white emission of 10 times or more of the sample (# 3) subjected to the wet oxidation treatment at 650 ° C. was observed. Here, the area intensity refers to an integral value of the emission intensity (that is, the area of the lower region of the spectrum). In addition, when these samples (# 3, # 4) were immersed in a 10% hydrofluoric acid aqueous solution for 5 minutes, photoluminescence was not observed. From this, it is considered that these samples (# 3, # 4) emitted light when carbon clusters 630 were embedded in the silicon oxide layer 640 (FIG. 3).

  Next, the photoluminescence of the samples (# 9 to 16) subjected to carbonization at 650 ° C. and 850 ° C. was evaluated. 9 to 12 are graphs showing emission spectra of these samples (# 9 to 16). In these graphs, the spectrum of a sample having a high porosity is indicated by a solid line, and the spectrum of a sample having a low porosity is indicated by a broken line.

  The graph of FIG. 9 shows the emission spectrum of porous silicon (samples # 11 and # 15) that was carbonized at 650 ° C. and wet-oxidized at 650 ° C. Photoluminescence was also observed in these samples. The peak wavelength of the sample with high porosity (# 11) was about 450 nm, which was shorter than the peak wavelength of about 500 nm with the sample with low porosity (# 15). For this reason, the light emission of the sample (# 15) having a low porosity was white, whereas the sample (# 11) having a high porosity was slightly bluish white.

  The graph of FIG. 10 shows an emission spectrum of porous silicon (samples # 9 and # 13) that was carbonized at 850 ° C. and wet oxidized at 650 ° C. Photoluminescence was also observed in these samples. Similar to the samples carbonized at 650 ° C. (# 11 and 15 in FIG. 9), the peak wavelength (about 430 nm) of the sample with high porosity (# 9) in the sample in FIG. It was shorter than the peak wavelength (about 500 nm) of the lower sample (# 13). The emission intensity was higher than that of the sample subjected to carbonization at 650 ° C.

  The graph of FIG. 11 shows the emission spectrum of porous silicon (samples # 12 and # 16) subjected to carbonization at 650 ° C. and wet oxidation at 800 ° C. In these samples, stronger photoluminescence was observed than samples subjected to wet oxidation at 650 ° C. (# 11, 15 in FIG. 9 and # 9, # 13 in FIG. 10). In the sample of FIG. 11 as well, the emission wavelength of the sample with high porosity (# 12) was shorter than the emission wavelength of the sample with low porosity (# 16).

  The graph of FIG. 12 shows an emission spectrum of porous silicon (samples # 10 and # 14) that was carbonized at 850 ° C. and wet-oxidized at 800 ° C. The emission intensity of these samples was lower than that of the samples (# 12 and # 16 in FIG. 11) that were carbonized at 650 ° C. and wet oxidized at 800 ° C., but wet oxidized at 650 ° C. It was higher than the samples (# 11, 15 in FIG. 9 and # 9, # 13 in FIG. 10). On the other hand, in the sample of FIG. 12, unlike the samples whose emission spectra are shown in FIGS. 9 to 11, the emission wavelength of the sample with high porosity (# 10) and the emission wavelength of the sample with low porosity (# 14). Was almost the same.

  From the above photoluminescence evaluation results, it is possible to obtain a light emitter with a wide emission spectrum width by selectively oxidizing the microcrystalline silicon 614 after carbonizing the porous silicon 600 (FIG. 3). understood. Further, it has been found that a light emitter is formed by embedding carbon clusters formed in pores 612 continuous from the surface in a silicon oxide layer 640 formed by oxidizing microcrystalline silicon 614.

[Effect of the first embodiment]
It is presumed that an illuminant having a wide emission spectrum width composed of silicon oxide in which carbon clusters are embedded emits light at the interface between the carbon clusters and silicon oxide. In the first embodiment, carbon clusters are formed in the pores of porous silicon having a large surface area per unit volume. After the formation of the carbon clusters, the silicon of the porous silicon is selectively oxidized, so that the carbon clusters are embedded in the silicon oxide while maintaining the shape dispersed in the pores of the porous silicon. Therefore, a light emitter having a wide area per unit volume at the interface between the carbon cluster and silicon oxide can be formed, and the light emission intensity of the light emitter having a wide emission spectrum width can be increased. The light emitter formed according to the first embodiment has a structure in which carbon clusters continuous from the surface toward the inside are embedded in the silicon oxide layer, reflecting the structure of the pores.

E. Second embodiment:
FIG. 13 is a flowchart showing a manufacturing process of the light emitter in the second embodiment. The manufacturing process of the light emitter in the second embodiment is different from the manufacturing process of the first embodiment shown in FIG. 2 in that step S40 is added. Other points are the same as the manufacturing process of the first embodiment.

In step S40, the porous silicon subjected to the selective oxidation process in step S30 is annealed. Specifically, the porous silicon that has been subjected to the selective oxidation treatment is disposed at the center of the chamber 110 of the heat treatment furnace 100 (FIG. 1), and the temperature of the heat treatment furnace 100 is raised to the annealing temperature. After the temperature rise, the temperature of the heat treatment furnace 100 is maintained at the annealing temperature until the annealing time elapses, and then the temperature lowering of the heat treatment furnace 100 is started. In this annealing process, dry argon is supplied to the chamber 110 during the period from the start of temperature increase to the end of temperature decrease. In the second embodiment, the annealing process is performed in a dry argon atmosphere. However, in general, the annealing process can be performed in an arbitrary atmosphere. However, the annealing treatment is preferably performed in a non-oxidizing gas atmosphere. As the non-oxidizing gas, hydrogen (H ₂ ), nitrogen, helium, argon, or the like can be used.

  The annealing temperature can be appropriately set in the range of 800 to 1300 ° C, but is more preferably set in the range of 900 to 1100 ° C. The annealing time is appropriately changed between 5 minutes and 6 hours depending on the annealing temperature and the like. However, the annealing treatment time is more preferably set to 10 minutes to 5 hours, and more preferably 30 minutes to 3 hours.

F. Example of the second embodiment:
[Create sample]
In the example of the second embodiment, first, porous silicon (sample # 4) prepared in the example of the first embodiment, which was carbonized at 1000 ° C. and selectively oxidized at 800 ° C. was prepared. . Next, the prepared sample was annealed. The annealing process was performed for 2 hours by supplying argon to the chamber 110. The annealing temperature was three conditions of 800 ° C., 1050 ° C., and 1150 ° C.

G. Sample evaluation of the second embodiment:
[Evaluation of photoluminescence]
The photoluminescence of the sample prepared as described above was evaluated. The evaluation method of photoluminescence is the same as the evaluation method in the first embodiment. FIG. 14 is a graph showing how the emission intensity (area intensity) changes due to the annealing treatment. The horizontal axis represents annealing conditions, and the vertical axis represents the emission intensity after annealing when the emission intensity of the sample (# 4) before annealing is 1. As shown in FIG. 14, the annealing intensity increased the emission intensity from about 7 times to 12 times.

[Effects of Second Embodiment]
As described above, in the second embodiment, the light emission intensity is increased by performing the annealing process on the sample obtained in the first embodiment. Therefore, according to the second embodiment, it is possible to further increase the emission intensity of the light emitter having a wide emission spectrum width.

1 is a schematic configuration diagram showing a schematic configuration of a light emitter manufacturing apparatus 10. FIG. The flowchart which shows the manufacturing process of the light-emitting body in 1st Embodiment. The schematic diagram which shows typically the state of the sample in the manufacturing process of the light-emitting body shown in FIG. Explanatory drawing which shows the transmission electron microscope observation result of the sample before and behind selective oxidation treatment. The graph which shows the result of having evaluated the state of silicon using Raman scattering. The graph which shows the result of having evaluated the state of silicon using Raman scattering. The graph which shows the result of having evaluated the state of carbon using Raman scattering. The graph which shows the evaluation result of photoluminescence intensity. The graph which shows the evaluation result of photoluminescence intensity. The graph which shows the evaluation result of photoluminescence intensity. The graph which shows the evaluation result of photoluminescence intensity. The graph which shows the evaluation result of photoluminescence intensity. The flowchart which shows the manufacturing process of the light-emitting body in 2nd Embodiment. The graph which shows the mode of the light emission intensity change by annealing treatment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Luminescent body manufacturing apparatus 100 ... Heat processing furnace 110 ... Chamber 120,130 ... Flange 122,132 ... Piping 140 ... Heater 142 ... Thermocouple 150 ... Temperature controller 200,300,400,500 ... Gas supply part 202,212, 222 ... Piping 210 ... Open / close valve 220 ... Flow control valve 302,312,322 ... Pipe 310 ... Open / close valve 320 ... Flow control valve 402,412,422 ... Pipe 410 ... Open / close valve 420 ... Flow control valve 502,512 ... Pipe 510 Open / close valves 520, 530, 540, 550 ... Flow rate control valves 522, 532 ... Branch piping 542, 552 ... Piping 560 ... Bubbler 600 ... Porous silicon 610 ... Porous layer 612 ... Pore 614 ... Microcrystalline silicon 620 ... Substrate 630 ... carbon cluster 640 ... silicon oxide layer 642 ... silicon oxide SMP ... Sample

Claims (8)

A method of manufacturing a light emitter,
(A) preparing porous silicon;
(B) forming carbon clusters in the pores formed in the porous silicon;
(C) selectively oxidizing silicon of the porous silicon on which the carbon clusters are formed;
With
The said process (b) is a light-emitting body manufacturing method including the process of heat-processing the said porous silicon in the gas atmosphere containing a hydrocarbon. A claim 1 Symbol placing illuminant manufacturing method,
The said process (c) is a light-emitting body manufacturing method including the process of heat-processing the said porous silicon in the inert gas atmosphere of a wet state. The method of manufacturing a light emitter according to claim 2 ,
The light emitting body manufacturing method, wherein the temperature of the heat treatment in the step (c) is a temperature of 600 ° C to 900 ° C. The method of manufacturing a light emitter according to any one of claims 1 to 3 , further comprising:
(D) A light emitting body manufacturing method comprising a step of heat-treating the porous silicon in which the silicon is selectively oxidized. The method of manufacturing a light emitter according to claim 4 ,
The light-emitting body manufacturing method, wherein a temperature of the heat treatment in the step (d) is 800 ° C to 1300 ° C. It is a light-emitting body manufacturing method of Claim 4 or 5 ,
The heat treatment in the step (d) includes a step of heat-treating the porous silicon in a non-oxidizing gas atmosphere.   A light emitter manufactured by the method for manufacturing a light emitter according to claim 1. The light emitter according to claim 7, wherein
The porous silicon is a light emitting body formed on a silicon substrate.

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