Author: Gilberto Vitor ZaiaPublisher:
ISBN:
Category :
Languages : en
Pages : 192
Book Description
Epitaxial Growth of Si and 3C-SiC by Chemical Vapor Deposition
Author: Gilberto Vitor ZaiaEpitaxial Growth of Silicon Carbide on On-axis Silicon Carbide Substrates Using Methyltrichlorosilane Chemical Vapor Deposition
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
4H-silicon carbide (4H-SiC) is a wide band gap semiconductor with outstanding capabilities for high temperature, high power, and high frequency electronic device applications. Advances in its processing technology have resulted in large micropipe-free single crystals and high speed epitaxial growth on off-axis silicon face substrates. Extraordinarily high growth rates of high quality epitaxial films (>100 [Mu]m per hour) have been achieved, but only on off-axis substrates (misoriented 4° to 8° from the (0001) crystallographic plane). There is a strong incentive to procure an on-axis growth procedure, due to the excessive waste of high quality single crystal associated with wafering off-axis substrates. The purpose of this research was to develop a reliable process for homoepitaxial growth of 4H-SiC on on-axis 4H-SiC. Typically the use of on-axis SiC for epitaxial growth is undesired due to the increased probability of 3C-SiC inclusions and polycrystalline growth. However, it is believed that the presence of chlorine during reaction may reduce the presence of 3C-SiC and improve the quality of the epitaxial film. Therefore homoepitaxial SiC was deposited using methyltrichlorosilane (MTS) and ethane sources with carrier gases consisting of argon-hydrogen mixtures. Ethane was used to increase the C/Si ratio, to aid in the prevention of 3C-SiC, and to help eliminate silicon droplets deposited during epitaxial growth. Deposition occurred in a homemade, quartz, cold wall chemical vapor deposition reactor. Epitaxial films on on-axis 4H-SiC were deposited without the presence of 3C-SiC inclusions or polycrystalline SiC, as observed by defect selective etching, scanning electron microscopy and optical microscopy. Large defect free areas, [similar to]5 mm[superscript]2, with epitaxial film thicknesses of [similar to]6 [Mu]m were grown on on-axis 4H-SiC. Epitaxial films had approximately an 80%, [similar to]20 cm[superscript]-2, decrease in defect density as compared to the substrates. The growth rate was independent of face polarity and orientation of the substrate. The optimal temperature for hydrogen etching, to promote the smoothest epitaxial films for on-axis substrates (both C- and Si-polarities), is [similar to]1550 °C for 10 minutes in the presence of 2 slm hydrogen. The optimum C/Si ratio for epitaxial growth on on-axis 4H-SiC is 1; excess carbon resulted in the codeposition of graphite and cone-shaped silicon carbide defects.
CVD growth of SiC for high-power and high-frequency applications
Author: Robin KarhuPublisher: Linköping University Electronic Press
ISBN: 9176851494
Category :
Languages : en
Pages : 40
Book Description
Silicon Carbide (SiC) is a wide bandgap semiconductor that has attracted a lot of interest for electronic applications due to its high thermal conductivity, high saturation electron drift velocity and high critical electric field strength. In recent years commercial SiC devices have started to make their way into high and medium voltage applications. Despite the advancements in SiC growth over the years, several issues remain. One of these issues is that the bulk grown SiC wafers are not suitable for electronic applications due to the high background doping and high density of basal plane dislocations (BPD). Due to these problems SiC for electronic devices must be grown by homoepitaxy. The epitaxial growth is performed in chemical vapor deposition (CVD) reactors. In this work, growth has been performed in a horizontal hot-wall CVD (HWCVD) reactor. In these reactors it is possible to produce high-quality SiC epitaxial layers within a wide range of doping, both n- and p-type. SiC is a well-known example of polytypism, where the different polytypes exist as different stacking sequences of the Si-C bilayers. Polytypism makes polytype stability a problem during growth of SiC. To maintain polytype stability during homoepitaxy of the hexagonal polytypes the substrates are usually cut so that the angle between the surface normal and the c-axis is a few degrees, typically 4 or 8°. The off-cut creates a high density of micro-steps at the surface. These steps allow for the replication of the substrates polytype into the growing epitaxial layer, the growth will take place in a step-flow manner. However, there are some drawbacks with step-flow growth. One is that BPDs can replicate from the substrate into the epitaxial layer. Another problem is that 4H-SiC is often used as a substrate for growth of GaN epitaxial layers. The epitaxial growth of GaN has been developed on on-axis substrates (surface normal coincides with c-axis), so epitaxial 4H-SiC layers grown on off-axis substrates cannot be used as substrates for GaN epitaxial growth. In efforts to solve the problems with off-axis homoepitaxy of 4H-SiC, on-axis homoepitaxy has been developed. In this work, further development of wafer-scale on-axis homoepitaxy has been made. This development has been made on a Si-face of 4H-SiC substrates. The advances include highly resistive epilayers grown on on-axis substrates. In this thesis the ability to control the surface morphology of epitaxial layers grown on on-axis homoepitaxy is demonstrated. This work also includes growth of isotopically enriched 4H-SiC on on-axis substrates, this has been done to increase the thermal conductivity of the grown epitaxial layers. In (paper 1) on-axis homoepitaxy of 4H-SiC has been developed on 100 mm diameter substrates. This paper also contains comparisons between different precursors. In (paper 2) we have further developed on-axis homoepitaxy on 100 mm diameter wafers, by doping the epitaxial layers with vanadium. The vanadium doping of the epitaxial layers makes the layers highly resistive and thus suitable to use as a substrate for III-nitride growth. In (paper 3) we developed a method to control the surface morphology and reduce the as-grown surface roughness in samples grown on on-axis substrates. In (paper 4) we have increased the thermal conductivity of 4H-SiC epitaxial layers by growing the layers using isotopically enriched precursors. In (paper 5) we have investigated the role chlorine have in homoepitaxial growth of 4H-SiC. In (paper 6) we have investigated the charge carrier lifetime in as-grown samples and traced variations in lifetime to structural defects in the substrate. In (paper 7) we have investigated the formation mechanism of a morphological defect in homoepitaxial grown 4H-SiC.
Epitaxial Growth and Optoelectronic Characterization of Cubic Silicon Carbide Deposited Using Chemical Vapor Deposition on Porous Silicon
Author: Frederick Paul VaccaroPublisher:
ISBN:
Category :
Languages : en
Pages : 406
Book Description
ABSTRACT: Cubic silicon carbide is a promising material for applications in high-power, high-frequency, high-temperature, and high-speed electronic devices. Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry (SIMS), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM) evaluations performed on thin films grown heteroepitaxially on porous (i.e. anodized) silicon using a new chemical vapor deposition (CVD) method employing trimethylsilane confirmed that the thin films were stoichiometric, cubic silicon carbide (3C-SiC). Conclusions were drawn on the basis of comparisons with published standards as well as with results generated on reference materials. SIMS profiles revealed the growth rates at approximately 1150̊C to vary from 2.1 to 4.0 Å/min. depending upon the slight variations in the CVD process trimethylsilane gas pressure. AFM evaluations revealed that the deposition mode at short deposition times was homo-oriented island nucleation and growth but that the 3C-SiC thin films evolved into continuous terraced layers at longer deposition times. Heterojunction (pn) junction diodes, fabricated from CVD and chemical vapor converted (CVC) porous silicon specimens, displayed world record breakdown voltages as high as 140 volts and 150 volts respectively. Historically, heterojunction (pn) junction diodes fabricated from 3C-SiC thin film specimens deposited on non-anodized displayed breakdown voltages below 10 to 20 volts.
Growth of 3C-SiC on (111)Si Using Hot-wall Chemical Vapor Deposition
Author: Christopher LockePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
ABSTRACT: The heteroepitaxial growth of cubic silicon carbide أ-سىأ) َُ(١١١) ٱىىٌك َُ(سى) ٱ�قٱفْٰمٰٱ، �ىف ف وىُْ“فَُٰ ٌو-ُٰ�ف ٌٌكومىٍكف ٌ�ف ُِْلمٱُِىىٰ َُ(أضؤ) مْفك،ُْٰ وفٱ قمم َفكوىم�مل. ا�ُْوٰ �فٱ كلَُ�كمٰل �ٱىهَ ف �ٰ ُٱمٰ ِكُِْمٱٱ: نىٱْ ٰوٰم سى ٱ�قٱفْٰمٰ ٱ�نْفكم ىٱ ك�َُممْٰل ُٰسىأ �ىف ف كفقْىَُ“فىٰ َُكُِْمٱٱ فلَ ٱمكلَُ وٰم ه�ُْوٰ نُ ٣أ-سىأ ىٱ مِنْمٍُْل َُوٰم ىىَىٰف ٌكفقْىَُ“مل فٌ”م.ْ ؤ�ىْهَ كفقْىَُ“فىٰ،َُ وٰم ٱ�نْفكم نُ وٰم سى ىٱ ك�َُممْٰل ُٰ٣أ-سىأ، �وىكو ومٱٌِ ُٰىٍىَىٍ“م وٰم ٱمْٰٱٱ ى َوٰم ه�ُْىهَ ك”ْٱفٰ.ٌ ذفُِْمَ (أ٣ب٨) فلَ ٱىفٌمَ (سىب٤)، لى�ٌمٰل ى َو”لهُْم َ(ب٢)، �ممْ �ٱمل فٱ وٰم كفقْ َُفلَ ٱىىٌك َُٱ�ُكْم، مْٱمِكىٰ�م”ٌ. ء لمٱُِىىٰ َُفْمٰ نُ ف٬ُِِْىفٍمٰ”ٌ ١٠ �ơ/ٍو �فٱ مٱفٰقىٌٱومل ل�ىْهَ وٰم ىىَىٰف ٌكُِْمٱٱ ف ٰف مٰمٍِفْ�ٰمْ نُ �١٣٨٠ ℗ʻأ. شوم ىُِٰىٍ“مل كُِْمٱٱ لُِْ�كمل نىٱٌٍ �ىوٰ ظ-فْ” كُْىًهَ ك��ْم ن�-ٌٌ�ىلوٰ ف ٰوفنٌ-فٍ٬ى�ٍ ٍ(ئطبح) �ف�ٌمٱ نُ ٢١٩ فكْٱمك، �وىكو ىٱ ٱىهىَنىكف”ٌَٰ قممٰٰ ْوٰف َف”َ وُٰم ْ�ِقىٌٱومل مْٱ�ٱٌٰ ى َوٰم ىٌمٰفْ�ٰمْ. دكَم وٰىٱ كُِْمٱٱ �فٱ لم�ممٌُِل ف �ٌُم ْمٰمٍِفْ�ٰمْ كُِْمٱٱ �فٱ لم�ممٌُِل ف ٰف ٱ�ٌُم ْه�ُْوٰ فْمٰ نُ �٢ �ơ/ٍو ف ٰ١٢٢٥ ℗ʻأ. شوم ك”ْٱفٰ ٌ�ّفىٌ”ٰ �فٱ ىنَمىْ ُْف ٰوٰم مْل�كمل مٰمٍِفْ�ٰمْ ق� ٰوٰىٱ مَ� كُِْمٱٱ ف�ٌٌُٱ ن ُْوٰم ه�ُْوٰ نُ ٣أ-سىأ(١١١) نىٱٌٍ َُ٬ُىلم مْمٌفٱم فٌ”مٱْ ن ُْحإحس فىٌِِكفىٰٱَُ. ة َفللىىٰ،َُ ن ُْممٌكىَُْٰك لم�ىكم فىٌِِكفىٰٱَُ، ف �ٌُم ْمٰمٍِفْ�ٰمْ كُِْمٱٱ مْل�كمٱ وٰم هممَفْىٰ َُنُ لمنمكٱٰ كف�ٱمل ق” وٰم مَف”ٌْ ٨ ٪ ىٍٱفٍكٰو ى َوٰم كمُننىكىم َٰنُ وٰمفٍْ ٌم٬فِٱَى َُ(أشإ) قم�ٰمم َ٣أ-سىأ فلَ سى. ئىفَ”ٌٌ ف مَ� كُِْمٱٱ �ٱىهَ ف ”ٌُِ-سى ٱممل فٌ”م ْلمٱُِىمٰل َُف َ٬ُىلم-كفُمٰل سى �فنم ْ�فٱ �ٱمل ُٰن ٍُْ٣أ-سىأ نىٱٌٍ ن ُْحإحس فىٌِِكفىٰٱَُ. شوم مْٱ�ٱٌٰ ىلَىكفمٰل ىىَىٰف”ٌٌ وٰف ٰوٰم نىٱٌٍ فٍ” م�م َقم كٍَُُ”ْٱفٰىٌٌمَ (قفٱمل َُظ-فْ” م�ف�ٌفىٰ)َُ ق� ٰفٌمٰ ْففَ”ٌٱىٱ مِنْمٍُْل �ٱىهَ شإح ىلَىكفمٰل وٰم” �ممْ وىهو”ٌ-لُْممْل ”ٌُِك”ْٱفٰىٌٌمَ نىٱٌٍ. شوم ه�ُْ َ٣أ-سىأ نىٱٌٍ �ممْ ففَ”ٌ“مل �ٱىهَ ف �فىْم”ٰ نُ كوففْكمٰىْ“فىٰ َُمٰكوىَ�ّمٱ. شوم وٰىكمًَٱٱ نُ وٰم نىٱٌٍ �فٱ فٱٱمٱٱمل وٰ�ُْهو ئ�ُىْم ْشفْٱَن ٍُْىنَفْمْل (ئشةز) ٱمِكٱُْٰك”ُِ، فلَ كنَُىمٍْل (ى َوٰم كفٱم نُ ه�ُْوٰ َُ”ٌُِ-سى ٱممل فٌ”مٱْ) ق” كٱُْٱ-ٱمكىٰ َُٱكفىََهَ ممٌك َُْٰىٍكٱُْك”ُِ (سإح). شوم سإح كٱُْٱ-ٱمكىٰٱَُ �ممْ فٱٌ ُ�ٱمل ُٰى�َمٱىٰهفمٰ وٰم ٣أ-سىأ/٬ُىلم ىمَٰنْفكم. شوم ٱ�نْفكم وٍُِْهٌُُ” نُ وٰم نىٱٌٍ �فٱ ىٱَمِكمٰل �ىف خفٍُٱْ”ً ىمَٰنْممْكَم ىُِٰكف ٌىٍكٱُْك”ُِ، فىٍُٰك نكُْم ىٍكٱُْك”ُِ (ءئح)، فلَ سإح. شوم ك”ْٱفٰىٌٌمَ �ّفىٌ”ٰ نُ وٰم نىٱٌٍ �فٱ لممٰىٍْمَل وٰ�ُْهو ظ-فْ” لىننفْكىٰ َُ(ظزؤ).
Selective Epitaxial Growth of Silicon Carbide on Silicon by Low- Temperature Chemical Vapor Deposition
Author: Ying GaoSelective Epitaxial Growth of Silicon Carbide on Silicon and Silicon Carbide Substrates by Chemical Vapor Deposition
Author: Brandy Kay BurklandEpitaxial Growth of Beta-silicon Carbide Thin Films by the Chemical Vapor Deposition Technique
Author: Hai-pyng Peter LiawPublisher:
ISBN:
Category : Epitaxy
Languages : en
Pages : 462
Book Description
CVD solutions for new directions in SiC and GaN epitaxy
Author: Xun LiPublisher: Linköping University Electronic Press
ISBN: 9175190842
Category : Gallium nitride
Languages : en
Pages : 57
Book Description
This thesis aims to develop a chemical vapor deposition (CVD) process for the new directions in both silicon carbon (SiC) and gallium nitride (GaN) epitaxial growth. The properties of the grown epitaxial layers are investigated in detail in order to have a deep understanding. SiC is a promising wide band gap semiconductor material which could be utilized for fabricating high-power and high-frequency devices. 3C-SiC is the only polytype with a cubic structure and has superior physical properties over other common SiC polytypes, such as high hole/electron mobility and low interface trap density with oxide. Due to lack of commercial native substrates, 3C-SiC is mainly grown on the cheap silicon (Si) substrates. However, there’s a large mismatch in both lattice constants and thermal expansion coefficients leading to a high density of defects in the epitaxial layers. In paper 1, the new CVD solution for growing high quality double-position-boundaries free 3C-SiC using on-axis 4H-SiC substrates is presented. Reproducible growth parameters, including temperature, C/Si ratio, ramp-up condition, Si/H2 ratio, N2 addition and pressure, are covered in this study. GaN is another attractive wide band gap semiconductor for power devices and optoelectronic applications. In the GaN-based transistors, carbon is often exploited to dope the buffer layer to be semi-insulating in order to isolate the device active region from the substrate. The conventional way is to use the carbon atoms on the gallium precursor and control the incorporation by tuning the process parameters, e.g. temperature, pressure. However, there’s a risk of obtaining bad morphology and thickness uniformity if the CVD process is not operated in an optimal condition. In addition, carbon source from the graphite insulation and improper coated graphite susceptor may also contribute to the doping in a CVD reactor, which is very difficult to be controlled in a reproducible way. Therefore, in paper 2, intentional carbon doping of (0001) GaN using six hydrocarbon precursors, i.e. methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), iso-butane (i-C4H10) and trimethylamine (N(CH3)3), have been explored. In paper 3, propane is chosen for carbon doping when growing the high electron mobility transistor (HEMT) structure on a quarter of 3-inch 4H-SiC wafer. The quality of epitaxial layer and fabricated devices is evaluated. In paper 4, the behaviour of carbon doping using carbon atoms from the gallium precursor, trimethylgallium (Ga(CH3)3), is explained by thermochemical and quantum chemical modelling and compared with the experimental results. GaN is commonly grown on foreign substrates, such as sapphire (Al2O3), Si and SiC, resulting in high stress and high threading dislocation densities. Hence, bulk GaN substrates are preferred for epitaxy. In paper 5, the morphological, structural and luminescence properties of GaN epitaxial layers grown on N-face free-standing GaN substrates are studied since the N-face GaN has advantageous characteristics compared to the Ga-face GaN. In paper 6, time-resolved photoluminescence (TRPL) technique is used to study the properties of AlGaN/GaN epitaxial layers grown on both Ga-face and N-face free-standing GaN substrates. A PL line located at ~3.41 eV is only emerged on the sample grown on the Ga-face substrate, which is suggested to associate with two-dimensional electron gas (2DEG) emission.
Growth of 3C-SiC Via a Hot-wall CVD Reactor
Author: Suzie HarveyPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
ABSTRACT: The heteroepitaxial growth of cubic silicon carbide (3C-SiC) on silicon (Si) substrates at high growth rates, via a horizontal hot-wall chemical vapor deposition (CVD) reactor, has been achieved. The final growth process was developed in three stages; an initial "baseline" development stage, an optimization stage, and a large area growth stage. In all cases the growth was conducted using a two step, carbonization plus growth, process. During carbonization, the surface of the Si is converted to 3C-SiC, which helps to minimize the stress in the growing crystal. Propane (C3H8) and silane (SiH4), diluted in hydrogen (H2), were used as the carbon and silicon source, respectively. A deposition rate of approximately 10 um/h was established during the baseline process. Once the baseline process proved to be repeatable, optimization of the process began. Through variations in temperature, pressure, and the Si/C ratio, thick 3C-SiC films (up to 22 um thick) and high deposition rates (up to 30 um/h) were obtained. The optimized process was then applied to growth on 50 mm diameter Si(100) wafers. The grown 3C-SiC films were analyzed using a variety of characterization techniques. The thickness of the films was assessed through Fourier Transform infrared (FTIR) spectroscopy, and confirmed by cross-section scanning electron microscopy (SEM). The SEM cross-sections were also used to investigate the 3C-SiC/Si interface. The surface morphology of the films was inspected via Nomarsky interference optical microscopy, atomic force microscopy (AFM), and SEM. The crystalline quality of the films was determined through X-ray diffraction (XRD) and low-temperature photoluminescence (LTPL) analysis. A mercury probe was used to make non-contact CV/IV measurements and determine the film doping.