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| sapphire substrate body |
GaN Epitaxial Semiconductor Substrate Body
Conventional silicon and gallium arsenide semiconductor materials were first-generation and second -generation representatives to promote the development of their microelectronics, photonics technology development , as a basis of the information technology has brought tremendous change people's lives.However, the performance limitations of the material itself , the first and second generations of semiconductor material can only work in an environment below 200 ℃ , and anti-radiation, high voltage breakdown performance and so can not meet the development of modern electronic technology for high-temperature , high-power , high-frequency , high-pressure and anti-radiation, capable of emitting blue new requirements. In this case , the choice of materials, new electronic devices launched the third generation of semiconductors, GaN and SiC wide bandgap semiconductor materials become the representative of the third generation.In the third -generation semiconductors,GaN materials, more and more people 's attention. GaN has many advantages: the band gap , high electron saturation velocity , good thermal conductivity, high breakdown electric field , low dielectric constant , good thermal stability , chemical stability . Thus, the third -generation semiconductor material properties will eventually cause them to be in the aerospace, exploration , nuclear energy development , satellite, communications, automotive engines, displays, new light source , laser printing, memory, and other fields have broad application prospects . As early as the 1970s, people began to explore the GaN growth process , but due to technical limitations material growth can not get high-quality GaN crystal. With the growth of technology development , has appeared in molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) and other new methods, which greatly promoted the research on GaN . Sapphire crystal as a substrate material, the GaN crystal has the same structure, with a high temperature chemical stability , thermal properties, and is easy to obtain large size and relatively cheap, etc. , although there is a big GaN lattice mismatch . With the growth of technology continues to improve , has been able to produce a quality epitaxy on sapphire
GaN crystal,( 0001 ) plane of the sapphire wafer has a practical application of the most desirable substrate material .
SOS Microelectronic Circuits
SOS (Silicon on Sapphire) microelectronic circuits , refers to the sapphire wafer ( 1-102 ) plane of a layer of a silicon single crystal grown by heteroepitaxial film , and then the silicon single crystal film technology for fabricating a semiconductor device . SOS microelectronic circuits due to having high speed, low power consumption and anti- radiation,etc.,so the watch type mobile phone , desktop or laptop computers, high-speed, high-frequency radio communications, small satellites , spacecraft , and the development of the space shuttle have a particularly important application . Sapphire and silicon have similar thermal expansion coefficient. In the ( 1-102 ) plane of the sapphire wafer and, using hetero-epitaxially grown layer method
( 100 ) plane of the silicon single crystal film , and then the silicon single crystal film fabricating a semiconductor device . Sapphire crystal structural integrity of the substrate is to guarantee access to the structural integrity of the main conditions for silicon single crystal film .
ZnO,InN,And Other Epitaxial Film Substrate Body
Temperature band gap of ZnO 3.37eV, corresponding to ultraviolet light for direct bandgap wurtzite structure Ⅱ - Ⅵ semiconductor crystals with similar semiconductor GaN, ZnS , compared , ZnO has higher exciton binding energy , and its value of 60meV, can greatly reduce the low temperature lasing threshold. Thus ZnO at room temperature or higher temperatures are expected to achieve the exciton gain, thus the low threshold to obtain short-wavelength lasers applications . Since the implementation of ZnO UV optically pumped lasing at room temperature after.
The growth of ZnO single crystal thin film , p-type doping research worldwide attracted the attention of many research groups . Sapphire by low cost and high crystal ZnO has been widely used as a substrate epitaxial layer .
In Ⅲ - Ⅴ nitride in , InN is attracting more and more attention . And GaN, AlN , compared , InN Has the smallest effective mass , in theory, has the highest carrier mobility , so that it is in high-speed micro Electronic devices has a broad application prospects. While Ⅲ - Ⅴ nitride , it also has the smallest
Direct band gap , and its value is about 0.8eV , which makes Ⅲ - Ⅴ nitride AlN emission wavelength from the ultraviolet (6.2eV) extending into the infrared region of InN (0.8eV), a light emitting device prepared in a suitable materials . However, preparation of InN single crystal is very difficult , so far people InN research is still in the initial stage , in foreign countries , Masuoka and others with MOVPE method on sapphire substrates have been the first successful single-crystal InN epitaxial film . In China, Xiao Hongling , who use radio frequency plasma-assisted molecular beam epitaxy (RF-MBE) method on sapphire substrate obtained crystals of good quality single crystal InN epitaxial film . Superconducting thin films such as YBa2Cu3O7 - δ (YBCO) of the microwave surface resistance Rs than conventional metal materials several orders of magnitude , can be used to design high-performance passive microwave devices, such as filters , resonators , delay lines . Sapphire crystal dielectric constant , low dielectric loss , microwave performance, mechanical strength, and thermal conductivity is high , the substrate is LaAlO3.
More than 20 times . Large areas of industrial production of sapphire single crystal materials have been relatively inexpensive price , and therefore is a good substrate material . As the ferroelectric substrate material : used ferroelectric memory , spatial light modulators, optical switches, etc. ferroelectric random access memory , infrared detectors , drive, optical modulators, displays , etc., with excellent performance compelling and use value.
Sapphire crystal as a substrate material , the demand on the international market is getting bigger, while the crystal quality and size requirements are also rising .
