Gallium phosphide
Gallium phosphide
CAS: 12063-98-8
Molecular Formula: GaP
Gallium phosphide - Names and Identifiers
| Name | Gallium phosphide |
| Synonyms | Ccris 4019 Gallium phosphide Galenium Phosphide galliummonophosphide |
| CAS | 12063-98-8 |
| EINECS | 235-057-2 |
Gallium phosphide - Physico-chemical Properties
| Molecular Formula | GaP |
| Molar Mass | 100.7 |
| Density | 4.13 g/mL at 25 °C |
| Melting Point | 1480 °C |
| Flash Point | 230°F |
| Water Solubility | Insoluble in water. |
| Appearance | Block |
| Specific Gravity | 4.1 |
| Color | Pale orange |
| Merck | 14,4353 |
| Storage Condition | Room Temprature |
| Refractive Index | 2.9 |
| MDL | MFCD00016109 |
| Physical and Chemical Properties | Orange transparent crystals. Melting point 1477 °c. The relative density was 4.13. Its decompression is 3.5±1MPa. Difficult to dissolve in dilute, concentrated hydrochloric acid, nitric acid. Is a semiconductor. |
Gallium phosphide - Risk and Safety
| Hazard Symbols | Xi - Irritant |
| Risk Codes | 36/37 - Irritating to eyes and respiratory system. |
| Safety Description | 26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
| UN IDs | 3288 |
| WGK Germany | 2 |
| RTECS | LW9675000 |
| FLUKA BRAND F CODES | 10-21 |
| TSCA | Yes |
Gallium phosphide - Reference Information
| resistivity (resistivity) | ~ 0.3 Ω-cm |
| crystal structure | Cubic, Sphalerite Structure - Space Group F(-4)3m |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| Semiconductor material | Gallium phosphide is abbreviated as Gap. It is a group III-V compound semiconductor synthesized from element gallium (Ga) and element phosphorus (P). Its high purity at room temperature is an orange-red transparent solid. Gallium phosphide is an important material for making semiconductor visible light-emitting devices and is mainly used for making rectifiers, transistors, light pipes, laser diodes and refrigeration elements, etc. Gallium phosphide and gallium arsenide are semiconductors with electroluminescent properties, and are the so-called third-generation semiconductors after germanium and silicon. GaAs light-emitting diodes have high quantum efficiency, exquisite and simple device structure, high mechanical strength and long service life, and can be applied to "optical phones". Unlike gallium arsenide, gallium phosphide is an indirect bandgap material. When an impurity capable of forming an isoelectronic trap is introduced, the luminous efficiency thereof is greatly improved, and light of different colors can be emitted according to the difference of the introduced impurity. For example, when nitrogen is doped in gallium phosphide, it emits green light, and when zinc-oxygen is doped, it emits red light. Therefore, gallium phosphide is an important material for making visible light emitting diodes and digital tubes and other photoelectric display devices. In addition, it can also be used to make photomultiplier tubes, photoelectric memories, high temperature switches and other devices. The melting point of gallium phosphide is 1467 ℃. Because it contains volatile phosphorus, the ionizing pressure of gallium phosphide is as high as 35 atmospheres at the melting point temperature, so synthesis and crystal growth must be carried out in a high-pressure vessel. Gallium phosphide crystals drawn from high-temperature melts often contain more defects such as gallium and phosphorus vacancies, which can condense into micro-defects due to supersaturation during cooling, thus affecting the luminous efficiency of the device. In order to reduce these defects, the solute synthesis diffusion method can be used for crystal growth, but the growth rate is slow and it is not easy to obtain large crystals. At present, epitaxially grown gallium phosphide thin films are mostly used in device fabrication, while bulk single crystals are only used as substrate materials. The solute diffusion method is used in industry to prepare gallium phosphide, that is, gallium and phosphorus form a temperature gradient for diffusion or gallium hydroxide and saturated phosphorus vapor react in a hydrogen stream to obtain gallium phosphide. |
| preparation of gallium phosphide single crystal | In 1968, S.J. Bass of the Royal Radar Company and others first reported the use of high-pressure liquid sealing Czochralski method Growth and preparation of gallium phosphide (GaP) single crystal. Since then, LEC method has become the only method for preparing GaP single crystal. Now it has developed to a mass production scale with an annual output of about 25t in the world. Its basic technological process is to synthesize GaP polycrystal from gallium and phosphorus with high purity (above 6N) in a high-pressure synthesis furnace, and then put the polycrystal material into a high-pressure single crystal furnace after cleaning treatment to draw single crystal. Its growth parameters are: furnace chamber pressure 5 ~ 6MPa, pull speed ≈ 10mm/h. At present, the specifications of GaP single crystal substrate used at home and abroad are: n-type dopant sulfur and silicon, diameter about 50mm, crystal orientation <111> or <100>, n =(2~8)× 1017/cm3,μ n about 100 cm2/(v s),EPD ≤ 4 × 105/cm2, thickness about 300 μm. |
| epitaxial growth | p-n junctions of GaP or GaAsP are grown on GaP substrates by liquid phase epitaxy or vapor phase epitaxy for the preparation of visible light emitting diodes (LED). At present, the epitaxial wafers used in mass production of red and green LEDs are mainly prepared by liquid phase epitaxy (LPE) technology. Most of the growth methods adopt cooling method (cooling method), and the operation processes include sliding boat method, impregnation method, double box method, etc. The equipment capacity is generally 20-50 pieces/time, and the vertical substrate frame can reach 200 pieces/time. Yellow and orange LEDs can also be prepared by gas phase epitaxy (VPE) technology, and the diameter of the substrate used is generally 50mm. Source of knowledge: China Metallurgical Encyclopedia Editor-in-Chief Committee "Metal Material Volume" Editorial Committee |
| application | since German scientist H.Walker proposed that III-V compounds have semiconductor properties in 1952, people have started to study the single crystal preparation and properties of III-V compounds including GaP. Due to the high dissociation pressure of GaP at the melting point, only small-size polycrystals could be grown by solution growth before 1968. At present, gallium phosphide (Gap) is widely used in the preparation of light emitting diodes (LED), which is the compound semiconductor device with the largest production volume. Although the energy band structure of gallium phosphide is of indirect transition type, the probability of interband recombination is very small, but the bound exciton recombination formed by isoelectronic traps can obtain quite high luminous efficiency. For example, nitrogen is doped in GaP, and nitrogen is in the lattice. The phosphorus position, nitrogen and phosphorus belong to the V group elements and are isoelectric, but the outer electron of the nitrogen atom is 8 less than that of the phosphorus atom. In this way, the nitrogen atom on the phosphorus site in the crystal lattice has a greater affinity for electrons than the phosphorus atom, and it is easy to capture electrons, and then capture holes due to the Coulomb force to form the so-called "bound excitons", which are equivalent electrons The formed isoelectronic trap can produce effective near-band gap composite radiation when recombined. When the nitrogen doping concentration is ≈ 1019/cm3, nitrogen is the green luminescent center. If the nitrogen doping concentration is higher (>1019/cm3), N-N pairs will be formed in the lattice. When the N-N pair is recombined, yellow light will be emitted and Zn-O pairs will be doped into GaP, Zn-O the pair will replace GaP molecules to form equivalent molecules, and can also become isoelectronic traps, and the bound excitons formed will emit red light. GaAsP with appropriate components (generally grown by VPE method) is grown on GaP substrate and mixed with a certain concentration of nitrogen or Zn-O pairs at the same time, which can also emit red, orange and yellow light. Gallium phosphide single crystal is the main substrate material for preparing red, green, yellow and orange four-color visible light LEDs. |
| use | used in semiconductors such as InGaAsP/InP with high solar cell conversion rate. A large number of light-emitting diodes are used to control lamps, display instruments or surface light-emitting elements. Phosphide semiconductors used in light-emitting diodes include GaP, GaAsP, etc. Red light-emitting diodes use GaP or GaAsP, etc. Yellow and orange light-emitting diodes are based on GaAsP. |
| production method | currently, gallium phosphide crystals are mainly prepared by liquid sealing technology and epitaxial method of high pressure single crystal furnace. The liquid-sealed Czochralski method adopts a high-pressure single-crystal furnace. Polycrystalline gallium phosphide is added to the alloy quartz crucible of the single-crystal furnace, and then vacuumed and melted. Under the pressure of 5.5 Mpa argon, boron trioxide liquid seal is used to pull the crystal. Due to the high decomposition pressure of gallium phosphide, under typical growth conditions, a certain amount of phosphorus overflows and interacts with boron trioxide, which makes the transparency of boron trioxide worse, and part of it condenses on the observation hole to hinder observation. For this reason, X-ray scanning and weighing methods can be used to control the crystal diameter to produce gallium phosphide single crystal products. Synthetic solute diffusion method (SSD method) puts gallium into a Shi Ying crucible. The gallium source temperature is between 1100 ℃ and 1150 ℃. The temperature at the bottom of the crucible where gallium phosphide is placed is between 1000 ℃ and 1050 ℃, and the phosphorus source temperature is 420 ℃. At this time, about 0.1 Mpa phosphorus vapor pressure is generated. The ionizing decompression pressure of gallium phosphide at 1150 ℃ is 0.67Pa. Therefore, gallium phosphide can grow stably under 0.1 Mpa phosphorus vapor pressure. At the beginning, phosphorus vapor reacts with the surface of gallium at high temperature to form a gallium phosphide film. This gallium phosphide is dissolved in the gallium liquid below and diffuses to the bottom of the crucible. Due to the low temperature at the bottom of the crucible, when the gallium phosphide exceeds the solubility, crystals will be precipitated. If the phosphorus source is sufficient, the gallium liquid will eventually become all Gallium phosphide crystals. Gallium phosphide epitaxial growth single crystals prepared by the above method are mainly used as substrates. Liquid and vapor phase epitaxy can be used to prepare thin film single crystals. Gallium phosphide liquid phase epitaxy methods mainly include impregnation method, rotation method and sliding boat method. At present, the sliding boat method is more commonly used. Gas phase epitaxy mainly includes: Ga-PCI3-H2;GaHCl-PH3-H2;GaP-H2O(HCl)-H2 system and MOCVD method (metal organic thermal decomposition gas phase growth method). Recently, InP and InP;aAsP multilayer semiconductors have developed components with functions such as optical amplification, optical calculation, and optical memory. |
| category | toxic substances |
| toxicity classification | low toxicity |
| acute toxicity | oral-mouse LD50: 8000 mg/kg |
| flammability hazard characteristics | toxic phosphorus oxide smoke from high heat |
| storage and transportation characteristics | warehouse ventilation and low temperature drying |
| fire extinguishing agent | dry powder, foam, sand, carbon dioxide, mist water |
Last Update：2024-04-10 22:29:15
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