JP3695049B2 - Method for producing microcrystalline compound optical semiconductor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a microcrystalline compound optical semiconductor.the body'sManufacturing methodTo the lawIt is related.
[0002]
[Prior art]
Conventionally, silicon has been used as a microcrystalline optical semiconductor for solar cells, image sensors, thin film transistors, electrophotographic photoreceptors, and the like.
[0003]
However, the band gap of microcrystalline silicon is about 1.5 eV, and in order to use sunlight light effectively, it is possible to widen the band gap to effectively use a wide range of light. There was a problem that I could not.
[0004]
In addition, a microcrystalline semiconductor including these elements is an indirect transition type, and cannot be used for a light-emitting element, so that its use is limited.
[0005]
Conventionally, as a microcrystalline material of a III-V group compound semiconductor, InN, which has a small band gap and absorbs in the visible region, is used in combination with amorphous silicon as disclosed in JP-A-2-192770. It is disclosed. However, InN has a band gap of 1.9 eV, and the end gap needs to be variable in a wide range in order to perform efficient light absorption and light emission over the entire visible range. On the other hand, crystalline GaN has a band gap of about 3.1 eV and is absorbed in the ultraviolet region. Currently, a buffer layer is widely used for the production of GaN crystals, but the structure of this film is not so clear, but the growth is performed at a temperature of about 600 ° C., lower than the crystal growth. When the film is formed at a temperature lower than the normal crystal growth, it seems to be a microcrystal. However, in the subsequent crystal growth, growth was performed at 800 to 1000 ° C., and these were used only for relaxing the lattice mismatch with the substrate, and the microcrystalline compound was not used as a single film.
[0006]
In addition, it has been reported that GaN of microcrystalline film containing hydrogen can be obtained by plasma CVD using organometallic compounds as Group III raw materials, but this microcrystalline film is insulative and functions as an optical semiconductor. There was nothing to do. [J. Knights, and R.A. A. Lujan, J .; Appl. Phys. , 42, 1291 (1978)]
[0007]
[Problems to be solved by the invention]
  The first object of the present invention is to improve the shortcomings of such microcrystalline III-V compound semiconductors, allowing a wide range of optical gaps to be freely selected, excellent photoconductivity characteristics, high-speed response, environmental resistance characteristics and resistance. Microcrystalline compound optical semiconductor that can be a new optoelectronic material with high temperature characteristics and optically active large area and low costIs to provide a method for producing a microcrystalline compound optical semiconductor that can be produced safely and at low cost.
[0010]
[Means for Solving the Problems]
The present invention contains a specific amount of hydrogen, Ga, and nitrogen as a microcrystalline III-V compound semiconductor, and eliminates the disadvantage of the conventional microcrystalline III-V compound as an optoelectronic material at a low temperature. It was completed by using improved materials and film formation methods to compensate for defects in the film with hydrogen and to include the dopant in an activated state.
[0015]
BookThe method for producing a microcrystalline optical semiconductor of the invention activates a compound containing at least nitrogen to a necessary energy state or excited species, and decomposes and / or activates an organometallic compound containing Ga element by reaction with the active species. Alternatively, separately added hydrogen and hydrogen compounds are activated to the required energy state and excited species, and by reacting with these active species, organometallic compounds containing Ga element are decomposed and / or activated, and active species containing nitrogen To make a III-V group compound film. In this way, the organic group is separated as a stable molecule from the organic metal even at a low temperature at which a microcrystalline film can be grown, and is not taken into the film, so that dangling defects can be removed during film growth, and the activity generated from the organic group It has been found that active impurities by hydrogen or hydrogen added separately or hydrogen compounds can reduce impurities to a very small amount by removing carbon on the surface of the film during film growth, thereby completing the present invention. Further, by selecting nitrogen as a group V, the composition ratio can easily maintain a stoichiometric state.
[0016]
That is, this microcrystalline compound optical semiconductor activates a compound containing a nitrogen element into active species or excited species that can cause a reaction with an organometallic compound containing Ga. If desired, it can be produced by reacting an organometallic compound containing an element of Al or In. As an activating means for activating a compound containing nitrogen or a compound containing hydrogen to a required energy state or excited species, discharge energy, for example, energy of high frequency discharge and / or microwave discharge can be used. . A gaseous raw material containing an element such as Al, Ga, In, or a gaseous raw material containing an element for controlling pn is introduced from the downstream side of each activating means.
[0017]
The optical semiconductor element of the present invention is characterized by using the above-described microcrystalline compound optical semiconductor as a photoconductive member, and further comprising at least one of a p-type microcrystalline compound optical semiconductor and an n-type microcrystalline compound optical semiconductor. It may be provided.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0019]
  Of the present inventionObtained by the manufacturing methodA microcrystalline compound optical semiconductor is a semiconductor characterized in that it contains a microcrystalline compound containing 5 atomic% or more and 40 atomic% or less of hydrogen, Ga, and a nitrogen element in its structure. It may contain more than one element. Al can range from 0.1 atomic percent to 99.9 atomic percent of the entire group III element, and In can range from 0.1 atomic percent to 99.9 atomic percent of the entire group III element. is there.
[0020]
The microcrystalline optical semiconductor contains the microcrystalline compound in its structure, but the semiconductor may be entirely composed of a phase composed of a microcrystalline compound, and the microcrystalline compound is contained in an amorphous phase. A dispersed mixed state may be used. In this mixed state, the proportion of the microcrystalline compound dispersed in the amorphous phase is preferably 20% by volume or more, and more preferably 30% by volume or more. This ratio can be measured by electron micrograph. It can also be calculated from the line width and peak intensity of the stretching vibration peak of the group V atom-N atom in the infrared absorption spectrum.
[0021]
The crystal system of the microcrystalline compound may be any one of a cubic system and a hexagonal system, or a plurality of crystal systems may be mixed.
[0022]
The size of the microcrystal is preferably 5 nm to 100 μm, and the size can be measured by a known method such as X-ray diffraction, electron beam diffraction, and shape measurement using a cross-sectional electron micrograph.
[0023]
If the size of the microcrystal is 5 nm or less, the crystal state cannot be confirmed even by the above method, and a desired effect may not be obtained after the semiconductor formation, which is not preferable. Even if the size of the microcrystal exceeds 100 μm, the function as a semiconductor is not deteriorated. However, the resistance of the crystal is higher than that of the crystal which is the object of the present invention, and lower than that of the amorphous film. From the viewpoint of obtaining a semiconductor, the above range is preferable.
[0024]
Hydrogen contained in the microcrystalline optical semiconductor is 0.5 atomic% to 40 atomic%, and more preferably 1 atomic% to 30 atomic%. When the hydrogen content is less than 0.5 atomic%, bond defects at the crystal grain boundaries, or bond defects and dangling bonds inside the amorphous phase are eliminated by bonding with hydrogen, and defect states formed in the band. Insufficient to inactivate the position, the amount of defects increases, the dark resistance decreases, the photosensitivity is lost, and it cannot function as a practical microcrystalline optical semiconductor.
[0025]
On the other hand, if the amount of hydrogen in the microcrystalline compound exceeds 40 atomic%, the probability that two or more hydrogen bonds to group III and group V elements increases, and these group III or group V elements maintain a three-dimensional structure. However, a two-dimensional and chain network is formed, and a large amount of voids are generated particularly at the crystal grain boundary. As a result, a new level is formed in the band. For this reason, electrical characteristics deteriorate and mechanical properties such as hardness decrease. Further, the film is easily oxidized, and a large amount of impurity defects are generated in the film, so that good photoelectric characteristics cannot be obtained.
[0026]
In addition, when the hydrogen content in the film exceeds 40 atomic%, the hydrogen is deactivated as a dopant to be doped for controlling electric characteristics, and as a result, an electrically active microcrystalline compound semiconductor cannot be obtained.
[0027]
  The atomic ratio of group III and nitrogen is preferably in the range of 1: 0.7 to 1: 1.5, and when the atomic ratio of group III and nitrogen is 1: 0.7 or less, or 1 : When the ratio is 1.5 or more, there are few portions of zinc-blende (Zincblende) type in the bond between group III and group V, the number of defects increases, and the semiconductor does not function as a good semiconductor.
[0028]
The microcrystalline optical semiconductor of the present invention is obtained by activating a compound containing a nitrogen element and reacting it with Ga or an organometallic compound containing this. Ga used here may be metal gallium, but it is preferable from the viewpoint of film structure control to react an organometallic compound containing Ga and, if desired, an organometallic compound containing an element of Al or In. Examples of the organometallic compound containing Ga used here include trimethyl gallium, triethyl gallium, and tert-butyl gallium.
[0029]
In addition, when a three-dimensional structure is realized as a whole film by microcrystals, dangling bonds are generated in both the group III element and the nitrogen element at the grain boundary. For this reason, it is desirable that the hydrogen that inactivates dangling bonds be bonded evenly to the group III element and the nitrogen element. In addition, when hydrogen is bonded to the dopant, substitutional impurity doping cannot be performed. Therefore, it is desirable that hydrogen not be bonded to the dopant. These hydrogen bonding states can be easily measured by an infrared absorption spectrum.
[0030]
Each elemental composition in the film can be measured by a known method such as X-ray photoelectron spectroscopy (XPS), electron microprobe, Rutherford backscattering (RBS). The absolute value of the amount of hydrogen can be measured by hydrogen forward scattering (HFS). It can also be estimated by measuring the amount of hydrogen released by heating or by measuring the IR spectrum.
[0031]
Next, the manufacturing method of the microcrystalline optical semiconductor of the present invention will be described.
The microcrystalline optical semiconductor of the present invention can be manufactured as follows.
[0032]
Hereinafter, it demonstrates according to a figure. FIG. 1 is a schematic view showing a semiconductor manufacturing apparatus having means for activating plasma suitable for manufacturing a microcrystalline optical semiconductor of the present invention.
[0033]
The semiconductor manufacturing apparatus 10 is provided with a container 14 that can be evacuated with an exhaust port 12, and a substrate holder 16 and a heater 18 for heating the substrate are disposed in the container 14. The container 14 communicates with quartz tubes 28 and 30 to which two gas introduction tubes 20 and 22 are connected. The gas introduction tube 20 is connected to the quartz tube 28, and the gas introduction tube is connected to the quartz tube 30. 22 is connected.
[0034]
In this apparatus 14, as a nitrogen element source, for example, N₂Gas is introduced into the quartz tube 28 from the gas introduction tube 20. A microwave of 2.45 GHz is supplied to a microwaveguide 24 connected to a microwave oscillator (not shown) using a magnetron, and a discharge is generated in the quartz tube 28. This discharge causes N in the quartz tube 28 to₂The gas is activated. This activation is an energy state and excited species necessary for causing a reaction with an organometallic compound containing Ga, that is, an energy state capable of breaking a Ga—C bond, a Ga—H bond, or a state changed to a radical. To be implemented.
[0035]
From another gas inlet 22, for example H₂Gas is introduced into the quartz tube 30. A high frequency of 13.56 MHz is supplied from a high frequency oscillator (not shown) to the high frequency coil 26 to generate a discharge in the quartz tube 30. Trimethylgallium is introduced from the third gas introduction tube 32 from the downstream side of the discharge space. The material activated in each of the quartz tubes 28, 30 is introduced into the container 14, where microcrystalline gallium nitride is formed on the substrate.
[0036]
Depending on the substrate temperature and the gas flow pressure, some of the compounds formed may become amorphous, and when the substrate temperature is high and / or when the group III source gas flow rate is low, it becomes microcrystalline. In order to form a desired microcrystalline compound, it is necessary to control these conditions. Those skilled in the art can appropriately perform this control. Generally, the substrate temperature is 100 ° C to 600 ° C. When the substrate temperature is lower than 300 ° C., it becomes microcrystalline when the flow rate of the group III source gas is small, and when the substrate temperature is higher than 300 ° C., it is fine even when the flow rate of the group III source gas is higher than the low temperature condition. It tends to be a crystal. These are controls for obtaining sufficient conditions for growing microcrystals, and when the substrate temperature is low and the flow rate of the group III source gas is high, the amorphous ratio increases, so care must be taken.
[0037]
An organometallic compound containing indium and aluminum can be mixed instead of trimethylgallium. Further, these organometallic compounds may be introduced from the gas introduction pipe 34.
[0038]
Further, a gas containing at least one element selected from C, Si, Ge, Sn, or a gas containing at least one element selected from Be, Mg, Ca, Zn, Sr is used in the discharge space. By introducing from the downstream side (the gas introduction pipe 34 or the gas introduction pipe 32), a microcrystalline nitride semiconductor of any conduction type such as n-type or p-type can be obtained. In the case of C, carbon of an organometallic compound may be used depending on conditions.
[0039]
In the apparatus as described above, active nitrogen or active hydrogen formed by discharge energy may be controlled independently, or NH_ThreeA gas containing nitrogen and hydrogen atoms at the same time may be used. Furthermore H₂May be added. Moreover, conditions under which active hydrogen is liberated from an organometallic compound can also be used. By doing so, activated group III atoms and nitrogen atoms exist on the substrate in a controlled state, and hydrogen atoms turn methyl and ethyl groups into inert molecules such as methane and ethane. Therefore, despite the low temperature, it is possible to produce a microcrystalline film with almost no carbon or a low amount and with suppressed film defects.
[0040]
In the above-described apparatus, the nitrogen compound activation means may be a high-frequency oscillator, a microwave oscillator, an electrocyclotron resonance system, a helicon plasma system, one of these, or two or more. It may be used. Further, both of them may be microwave oscillators, or both of them may be high frequency oscillators. In the case of high frequency discharge, it may be inductive or capacitive. Alternatively, the two may use an electron cyclotron resonance method. When different activation means (excitation means) are used, it is necessary to allow discharge to occur simultaneously at the same pressure, and a pressure difference may be provided between the discharge and the film forming unit (in the container 14). Further, when the same pressure is used, different activation means (excitation means), for example, microwave and high frequency discharge, can greatly change the excitation energy of the excited species, which is effective for film quality control.
[0041]
The microcrystalline compound semiconductor of the present invention can be produced by reactive vapor deposition or ion plating.TeeIt is also possible to perform film formation in an atmosphere in which at least hydrogen is activated, such as etching and reactive sputtering.
[0042]
The substrate used in the present invention may be conductive or insulating, and may be crystalline or non-quality. Examples of the conductive substrate include metals such as aluminum, stainless steel, nickel, and chromium, and alloy crystals thereof, and semiconductors such as Si, GaAs, SiC, and ZnO.
[0043]
In addition, an insulating substrate having a conductive surface applied to the substrate surface can be used. Examples of the insulating substrate include a polymer film, glass, quartz, and ceramic. The conductive treatment is performed by depositing the above metal or gold, silver, copper or the like by vapor deposition, sputtering, ion plating, or the like.
[0044]
In addition, as a transparent support for a transparent conductive substrate for light input / output, transparent inorganic materials such as glass, quartz, and sapphire, fluorine resin, polyester, polycarbonate, polyethylene, polyethylene terephthalate, epoxy, etc. Transparent organic resin films or plates, optical fibers, selfoc optical plates and the like can also be used.
[0045]
As the translucent electrode provided on the translucent support, a transparent conductive material such as ITO, zinc oxide, tin oxide, lead oxide, indium oxide, copper iodide is used, vapor deposition, ion plating, sputtering, etc. The one formed by the above method, or the one formed by thinning metal such as Al, Ni, Au or the like so as to be translucent by vapor deposition or sputtering is used.
[0046]
As a raw material for the microcrystalline compound optical semiconductor of the present invention, an organometallic compound containing Ga and optionally one or more elements selected from Al and In can be used. As these organometallic compounds, liquids and solids such as trimethylaluminum, triethylaluminum, tert-butylaluminum, trimethylgallium, triethylgallium, tert-butylgallium, trimethylindium, triethylindium, and tert-butylindium can be vaporized independently. Alternatively, it can be used in a mixed state by bubbling with a carrier gas. Carrier gas is hydrogen, N₂, Hydrocarbons such as methane, ethane, CF_Four, C₂F₆Halogenated carbon such as can be used.
[0047]
N as nitrogen raw material₂, NH_Three, NF_Three, N₂H_FourIt can be used by vaporizing or bubbling a gas or liquid such as methylhydrazine with a carrier gas.
[0048]
In the microcrystalline compound optical semiconductor of the present invention, an element can be doped into the film for p and n control.
[0049]
Elements for the n-type include: Group Ia Li, Group Ib Cu, Ag, Au, Group IIa Mg, Group IIb Zn, Group IVa Si, Ge, Sn, Pb, Group VIa S, Se, Te Can be used.
[0050]
Elements for the p-type include Group Ia Li, Na, K, Group Ib Cu, Ag, Au, Group IIa Be, Mg, Ca, Sr, Ba, Ra, Group IIb Zn, Cd, Hg, IVa Group C, Si, Ge, Sn, Pb, Group VIa S, Se, Te, Group VIb Cr, Mo, W, Group VIIa Fe, Co, Ni, etc. can be used.
[0051]
In order to prevent the hydrogen in the film from being bonded to the dopant and being inactivated, the hydrogen for passivating the defect level needs to be selectively bonded to the group III element and the nitrogen element rather than the dopant. In particular, Si, Ge, and Sn are particularly preferable as the n-type element, and Be, Mg, Ca, Zn, and Sr are particularly preferable as the p-type element.
[0052]
The doping method is SiH for n-type._Four, Si₂H₆, GeH_Four, GeF_Four, SnH_Four, BeH for p-type₂, BeCl₂, BeCl_Four, Cyclopentadienyl magnesium, dimethyl calcium, dimethyl strontium, dimethyl zinc, diethyl zinc, and the like. In order to dope the element into the film, a known method such as a thermal diffusion method or an ion implantation method can be employed.
[0053]
In order to form an optical semiconductor element using the microcrystalline optical semiconductor of the present invention, an unope film, p-type, i-type, or n-type microcrystalline optical semiconductor film may be provided on the substrate, or p. A n-type film and a pn junction may be formed, or an i-type film may be provided between the p-type and n-type films. Further, a film p + or n + layer doped with a higher concentration than p-type and n-type may be inserted between the electrodes for contact with the electrodes. A multilayer structure having pn or pin as a structural unit can also be formed. Furthermore, these p-type, i-type, and n-type layers may have different Al, Ga, In, and N compositions for transparency and barrier formation, or p-type, i-type, and n-type. Each film may be composed of a plurality of compositions.
[0054]
The thickness of each layer may be from 1 nm to several tens of μm. Lamination and repetition of the same film thickness may be used, or lamination and repetition of different film thicknesses may be used, and these layer configurations should be appropriately set according to the desired light absorption rate of the optical semiconductor element, the electric field of the active portion, the barrier length, etc. Can do.
[0055]
Such an optical semiconductor element using a microcrystalline optical semiconductor containing at least hydrogen, Ga, and a nitrogen element, and optionally having a microcrystalline compound containing one or more elements of B, Al, and In in its structure. The band gap is variable in the entire range from red to ultraviolet, and with high light transmission, high light sensitivity, and high-speed response, it can be used alone or as a tandem type combining layers with different absorption regions. A wide range of light from visible to ultraviolet can be used effectively.
[0056]
In addition, this optical semiconductor element has excellent light resistance, heat resistance, and oxidation resistance, and is capable of high-speed response. In addition, it has a light emitting function that does not exist in conventional microcrystalline semiconductors in all wavelength regions, so it can emit light from electronic devices. It can also be used for hybrid devices that combine devices. Specific examples include high-efficiency solar cells, high-speed TFTs, electrophotographic photoreceptors, high-sensitivity light sensors, high-sensitivity avalanche light sensors, large-area LEDs, full-color flat displays, light modulators, and optical interconnect elements.
[0057]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
Example 1
The cleaned Al substrate, quartz substrate, and Si wafer were placed on the substrate holder 16, the inside of the container 14 was evacuated through the exhaust port 12, and the substrate was heated to 350 ° C. by the heater 18.
[0058]
N₂Gas was introduced into the quartz tube 28 having a diameter of 25 mm from the gas introduction tube 20, and a microwave of 2.45 GHz was set to an output of 300 W through the microwave waveguide 24, matching was performed with a tuner, and discharge was performed. The reflected wave at this time was 0 W. H₂100 sccm of gas was introduced into the quartz tube 30 having a diameter of 30 mm from the gas introduction tube 22. The microwave output was set to 300W. The reflected wave was 0W. In this state, 1 sccm of trimethylgallium (TMGa) vapor kept at room temperature from the gas introduction tube 12 was directly introduced through the mass flow controller. At this time, the reaction pressure measured with a Baratron vacuum gauge was 0.2 Torr.
[0059]
When the film thickness was measured by the step measurement, it was 0.5 μm. When the film composition was measured by XPS and RBS (Rutherford Bucks Catering), it was found that the Ga / N ratio was 1.1 and was almost equal to the stoichiometry. At this time, carbon (C) was 5 atomic% or less, and oxygen (O) could not be detected.
[0060]
The optical gap was 3.2 eV. Further, hydrogen was 10 atomic% by HFS measurement. Hydrogen was contained in the GaN film as Ga-H and NH as a result of IR spectrum measurement. In the electron diffraction spectrum, a clear bright spot was observed, indicating that crystals were formed. When the cross section was measured with a transmission electron microscope, the size of the crystal was about 1 μm.
[0061]
When the resistance of the microcrystalline GaN film was measured, it was 1.5 × 10⁺⁸Ωcm and irradiated with Xe lamp light, 3.5 × 10^FourIt became Ωcm, and it was found that the photoconductivity with a light / dark ratio of 4 digits or more was exhibited.
(Example 2)
H₂Film formation was performed under the same conditions as in Example 1 except that the gas was discharged at a high frequency of 13.56 MHz with an output of 100 W via the high-frequency coil 26.
[0062]
The obtained film composition had a Ga / N ratio of 0.99, almost a stoichiometric ratio, and a hydrogen content of 13 atomic%. The optical gap was 3.2 eV. In the electron diffraction spectrum, a clear bright spot was observed, indicating that crystals were formed. When the cross section was measured with a transmission electron microscope, the size of the crystals was in the range of 0.3 to 0.7 μm. Dark resistance is 1 × 10⁺⁹The resistance to light and dark was 4 digits or more.
(Example 3)
Using the same apparatus and substrate as in Example 1, N₂Gas was introduced at 1000 sccm from the gas introduction tube 20, and a microwave output of 2.45 GHz was discharged at 300W.
[0063]
At this time, the reflected wave was 0 W. H₂Gas 300 sccm was introduced from the gas inlet tube 22 and discharged at a high frequency of 13.56 MHz and an output of 100 W. At this time, the reflected wave was 0 W. The temperature of the substrate holder 16 was set to 300 ° C. by the heater 18.
[0064]
In this state, trimethylindium heated to 50 ° C. at 0.5 sccm of trimethylgallium from the gas introduction pipe 32 is replaced with N.₂0.5 sccm mixed with gas and introduced. Further, N from the gas introduction pipe 34₂SiH diluted to 0.1% with gas_FourN-type a-Ga_xIn_yN_zWas deposited. The pressure was 0.2 Torr. After film formation for 30 minutes, the valves of the gas introduction pipe 32 and the gas introduction pipe 34 were closed. At this time, the discharge was continued as it was. In this state, a mixed gas of 0.5 sccm of trimethylgallium and 0.5 sccm of trimethylindium is introduced again from the gas introduction pipe 34, and bispentadienylmagnesium is introduced from the gas introduction pipe 32 as a carrier gas.₂1 sccm was introduced using p-type a-Ga._xIn_yN_zWas formed for 30 minutes.
[0065]
The film thickness of the obtained film was 0.3 μm. The composition of this film is Ga_x/ In_y/ N_zWas 0.65 / 0.35 / 1.1 and hydrogen was 15 atomic%. The overall optical gap of this film was 2.8 eV.
[0066]
In the electron diffraction spectrum, a clear bright spot was observed, indicating that crystals were formed. When the cross section was measured with a transmission electron microscope, the size of the crystals was in the range of 0.1 to 0.5 μm. A 100 A Au electrode capable of transmitting light to the film on the Al substrate and Au electrodes were vapor deposited on the top and bottom of the Si wafer and irradiated with an Xe lamp. A photovoltaic voltage of 0.8 V was obtained at an open voltage.
Example 4
Using the same apparatus and substrate as in Example 2, N₂Gas was introduced at 1000 sccm from the gas introduction tube 20, and a microwave output of 2.45 GHz was discharged at 300W.
[0067]
At this time, the reflected wave was 0 W. H₂100 sccm of gas was introduced from the gas introduction tube 22 and discharged at a high frequency of 13.56 MHz and an output of 300 W. At this time, the reflected wave was 0 W. The temperature of the substrate holder was set to 400 ° C. by the heater 18.
[0068]
In this state, 1 sccm of trimethylgallium was introduced from the gas introduction tube 32. The film composition was found to be approximately equal to stoichiometric with a Ga / N ratio of 1.05. Moreover, hydrogen by HFS measurement was 5 atomic%. The optical gap was 3.1 eV. In the electron diffraction spectrum and X-ray diffraction spectrum, clear bright spots and peaks were observed, indicating that the crystal was a microcrystal.
[0069]
When the cross section was measured with a transmission electron microscope, the size of the crystals was in the range of 1.0 to 5.0 μm. When the resistance of the microcrystalline GaN film was measured, it was 2.5 × 10.⁺⁷When it is Ωcm and irradiated with Xe lamp light, 5 × 10^ThreeIt became Ωcm, and it was found that the photoconductivity with a light / dark ratio of 4 digits or more was exhibited.
(Example 5)
A film was produced under the same conditions as in Example 4 except that the substrate temperature was 250 ° C.
[0070]
The film composition was found to be approximately stoichiometric with a Ga / N ratio of 0.98. The hydrogen content by HFS measurement was 28 atomic%. The optical gap was 3.2 eV. In the electron diffraction spectrum, a clear bright spot was seen in a hazy pattern, and it was found to be a microcrystalline film. When the cross section was measured with a transmission electron microscope, the size of the crystals was in the range of 10 to 50 nm. When the resistance of the microcrystalline GaN film was measured, 4.0 × 10⁺¹²When it is Ωcm and irradiated with Xe lamp light, 3 × 10⁷It became Ωcm, and it was found that the photoconductivity with a light / dark ratio of 4 digits or more was exhibited.
(Example 6)
Using the same apparatus and substrate as in Example 2, N₂A gas was introduced at 900 sccm from the gas introduction tube 20 and a microwave output of 2.45 GHz was discharged at 250 W. At this time, the reflected wave was 0 W. H₂Gas 300 sccm was introduced from the gas inlet tube 22 and no discharge was performed. The temperature of the substrate holder 16 was set to 250 ° C. by the heater 18.
[0071]
In this state, 3 sccm of trimethylgallium was introduced from the gas introduction tube 32. It was found that the film composition of the obtained film was approximately equal to the stoichiometry with a Ga / N ratio of 0.97. Moreover, carbon (C) was 12 atomic% at this time. Oxygen (O) was 0 atomic%. Moreover, it was 25 atomic% when the amount of hydrogen was calculated | required from IR absorption spectrum based on the sample of Examples 1-5 by HFS measurement. The optical gap was 3.4 eV. The electron diffraction spectrum and the X-ray diffraction spectrum showed a bright spot in a hazy pattern and were found to be a microcrystalline film. When the cross section was measured with a transmission electron microscope, it was confirmed that the crystal size was 5 to 20 nm. When the light-to-dark resistance ratio was measured by irradiating the microcrystalline GaN film with Xe lamp light, it was found that the photoconductivity was 4 digits or more.
(Comparative example)
Using the same apparatus and substrate as in Example 1, N₂Gas was introduced at 1000 sccm from the gas introduction tube 20, and a microwave output of 2.45 GHz was discharged at 300W. At this time, the reflected wave was 0 W. H₂50 sccm of gas was introduced. The temperature of the substrate holder 16 was set to 450 ° C. by the heater 18.
[0072]
In this state, 0.5 sccm of trimethylgallium was introduced from the gas introduction tube 20. It was found that the film composition of the obtained film was almost equal to the stoichiometry with a Ga / N ratio of 1.03.
[0073]
Moreover, the hydrogen amount measured using the calibration curve of HFS measurement and IR absorption intensity was 0.4 atomic%. The optical gap was 3.2 eV. In the electron diffraction spectrum and the X-ray diffraction spectrum, clear bright spots and peaks were observed, and the film was found to be a microcrystalline film.
[0074]
When the resistance of the microcrystalline GaN film was measured, it was 2.5 × 10.⁺⁶When it is Ωcm and irradiated with Xe lamp light, 5 × 10^FourIt became Ωcm, and it was found that photoconductivity with a light / dark ratio of 2 digits or more was shown, but it took several hours or more to reach equilibrium after light irradiation, and it was abrupt even after Xe lamp light irradiation was stopped. No decrease in current value was observed, and there was almost no change in conductivity due to on / off of light irradiation in a short time.
[0075]
【The invention's effect】
As described above, according to the microcrystalline compound optical semiconductor of the present invention, it is possible to effectively use a wide range of light from visible light to ultraviolet light due to high light transmittance, high light sensitivity, and high-speed response, as well as light resistance and heat resistance. It is excellent in stability and oxidation resistance, and has high-speed response. Utilizing these properties, it can be used in various optical semiconductor elements. Further, according to the manufacturing method of the present invention, a microcrystalline optical semiconductor having the above characteristics can be manufactured safely and at low cost. Furthermore, the optical semiconductor element of the present invention has an excellent characteristic that a wide range of light from visible to ultraviolet light can be effectively used due to high photosensitivity and high-speed response.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a preferred embodiment of an apparatus for producing an amorphous optical semiconductor of the present invention.
[Explanation of symbols]
10 Semiconductor manufacturing equipment
12 Exhaust port
14 Vacuum container
16 Substrate holder
18 Heater
20, 22 Gas introduction pipe
28, 30 quartz tube
24 Microwaveguide
26 High frequency coil
32, 34 Gas introduction pipe

Claims (2)

  A compound containing a nitrogen element is activated to an energy state or excited species necessary for causing a reaction with an organometallic compound containing Ga, and is not activated with a compound containing these activated nitrogen elements. A method for producing a microcrystalline compound optical semiconductor, comprising reacting an organometallic compound containing Ga and activating the organometallic compound containing Ga. 2. The method for producing a microcrystalline compound optical semiconductor according to claim 1 , wherein the means for activating the compound containing nitrogen element is application of discharge energy.

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