• Journal of IKEEE
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• v.23 no.1
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• pp.326-329
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• 2019

Gallium nitride(GaN) has been a superior candidate for the next generation power electronics. As GaN-on-Si substrate technology is mature, there has been new demand for monolithic integration of GaN technology with Si CMOS devices. In this work, (110)Si CMOS process was developed and the fabricated devices were evaluated in order to confirm the feasibility of utilizing domestic foundry facility for monolithic integration of Si CMOS and GaN power devices.

• Journal of the Korean Vacuum Society
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• v.11 no.1
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• pp.50-58
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• 2002

The growth of GaN films on Si substrate has many advantages in that Si is less expensive than sapphire substrate and that integration of GaN-based devices with Si substrate is easier The difference of lattice constant and thermal expansion coefficient between GaN and Si is larger than those between GaN and sapphire. However, which results in many defects into the grown GaN. In order to obtain high duality GaN films on Si substrate, we need to reduce defects using the buffer layer such as AlN. In this study, we prepared three types of AlN buffer layer with various crystallinity on Si (111) substrate using MOCVD, Sputtering and MOMBE methods. GaN was grown by MOCVD on three types of AlN/Si substrate. Using TEM and XRD, we carried out comparative investigation of growth and properties of GaN deposited on the various AlN buffers by characterizing lattice coherency, crystallinity, growth orientation and defects formed (voids, stacking faults, dislocations, etc). It is found that the crystallinity of AlN buffer layer has strong effects on growth of GaN. The AlN buffer layers grown by MOCVD and MOMBE showed the reduction of out-of-plane misorientation of GaN at the initial growth stage.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.91-97
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• 2013

Self-heating effects during operation of high current AlGaN/GaN power transistors degrade the current-voltage characteristics. In particular, this problem becomes serious when a low thermal conductivity Si substrate is used. In this work, AlGaN/GaN-on-Si devices were fabricated with various channel widths and Si substrate thicknesses in which the structure dependent self-heating effects were investigated by temperature dependent measurements as well as thermal simulation. Accordingly, a device structure that can effectively dissipate the heat was proposed in order to achieve the maximum current in a multi-channel, large area device. Employing via-holes and common electrodes with a 100 ${\mu}m$ Si substrate thickness improved the current level by 75% reducing the channel temperature by 68%.

• Journal of Surface Science and Engineering
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• v.36 no.2
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• pp.135-140
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• 2003

The difference in lattice parameter and thermal expansion coefficient between GaN and Si which results in many defects into the grown GaN is larger than that between GaN and sapphire. In order to obtain high quality GaN films on Si substrate, it is essential to understand growth characteristics of GaN. In this study, GaN layers were grown on Si(111) substrates by MOCVD at three different GaN growth temperatures ($900^{\circ}C$, $1,000^{\circ}C$ and $1,100^{\circ}C$), using AlN and LT-GaN buffer layers. Using TEM, we carried out the comparative investigation of growth characteristics of GaN by characterizing lattice coherency, crystallinity, orientation relationship and defects formed (transition region, stacking fault, dislocation, etc). The localized region with high defect density was formed due to the lattice mismatch between AlN buffer layer and GaN. As the growth temperature of GaN increases, the defect density and surface roughness of GaN are decreased. In the case of GaN grown at $1,100^{\circ}$, growth thickness is decreased, and columns with out-plane misorientation are formed.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.201-206
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• 2005

In this work, we tried to improve the fabrication process in HVPE (Hydride Vapor Phase Epitaxy) system by using Si(111) substrate with pre-deposited Al layer. PL measurements was done for samples with and without pre-deposited Al on Si and it was also examined the dependence of the optical characteristic properties on AlN buffer thickness for GaN/AIN/Al/Si. A sample with thin Al nucleation layer on Si substrate reveals a better optical property than the other. And it suggests that the thickness for AlN buffer layer with thin Al nucleation layer on Si(111) substrate is most proper about $260{\AA}$ to grow GaN in HVPE system. The surface morphology of GaN clearly shows the hexagonal crystallization. The XRD pattern showed strong peak at GaN{0001} direction.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.67-71
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• 2014

An attempt to grow high quality GaN on silicon substrate using metal organic chemical vapor deposition (MOCVD), herein GaN epitaxial layers were grown on various Si(111) substrates. Thin Platinum layer was deposited on Si(111) substrate using sputtering, followed by thermal annealing to form Pt nano-clusters which act as masking layer during dry-etched with inductively coupled plasma-reactive ion etching to generate nano-patterned Si(111) substrate. In addition, micro-patterned Si(111) substrate with circle shape was also fabricated by using conventional photo-lithography technique. GaN epitaxial layers were subsequently grown on micro-, nano-patterned and conventional Si (111) substrate under identical growth conditions for comparison. The GaN layer grown on nano-patterned Si (111) substrate shows the lowest crack density with mirror-like surface morphology. The FWHM values of XRD rocking curve measured from symmetry (002) and asymmetry (102) planes are 576 arcsec and 828 arcsec, respectively. To corroborate an enhancement of the growth quality, the FWHM value achieved from the photoluminescence spectra also shows the lowest value (46.5 meV) as compare to other grown samples.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.165-165
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• 2003

The growth of GaN on Si is of great interest due to the several advantages low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate [1]. In this work, the properties of GaN overlayer grown on ion implanted Si(111)and bare Si(111) have been investigated. Si(111) surface was treated ion implantation with 60KeV and dose 1${\times}$10$\^$16//$\textrm{cm}^2$ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 15-30 minutes at 1100$^{\circ}C$ with metal organic chemical vapor deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction (XRD), Scanning electron microscope (SEM) Photoluminescence (PL) at room temperature and Hall measurement The results showed that the GaN on ion implanted Si(111) markedly affected to the structural, optical and electrical characteristic of GaN layers.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.599-603
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• 1999

We have investigated the growth characteristics of thick GaN on Sim substrate with AlN and low temperature GaN buffer layer. The vertical hydride vapor phase epitaxy system with $GaCl_3$ precursor was used for growth of GaN. AlN and GaN buffer layer were deposited on Si substrate to reduce the lattice mismatch and the thermal expansion coefficient mismatch between si and GaN. Optimization of deposition condition for AlN and low temperature GaN buffer layers were carried out. We studied the effects of growth temperature, V/III ratio on the properties of thick GaN. Surface morphology, growth rate and crystallinity of thick GaN were measured using Atomic Force Microscopy (AFM), $\alpha-step$-, Scanning Electron Microscopy (SEM) and X-Ray Diffractometer(XRD).

• Journal of IKEEE
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• v.24 no.4
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• pp.1117-1121
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• 2020

In this work, it was confirmed that a SnO2 catalyst deposited by an atomic layer deposition(ALD) process can be employed in AlGaN/GaN heterostructure FET to detect NO2 gas. The fabricated HFET sensors on AlGaN/GaN-on-Si platform demonstrated that the devices with or without n-situ SiN have sensitivity of 5.5 % and 38 % at 200 ℃, respectively with response to 100 ppm-NO2.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.105-105
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• 2003

InGaN/GaN MQW 구조는 청색 및 녹색 범위의 밴드 갭을 가지는 반도체로 최근 LED 및 LD 제조 등에 이용되고 있다. InGaN/GaN MQW은 InGaN와 GaN의 최적 성장온도의 중간온도에서 실행된다. InGaN와 GaN는 최적 성장온도의 차이가 크므로 중간온도에서 성장 시에 많은 결함이 생긴다. 성장온도가 높으면 InN가 분해되고 낮을 경우에는 질소의 결핍이 일어난다. 최적성장온도의 선택이 매우 중요한 문제로 주목되었다. Si 도핑으로 중간온도 성장 시에 형성되는 결함을 감소시키고 광학적 특성을 향상시킨다고 보고되었다. 그러나, Si 도핑효과에 대한 구체적이고 체계적인 연구는 부족한 실정이다. MQWs 구조의 GaN 장벽층에 미치는 성장온도와 Si 도핑 효과를 이해하기 위해서는 고온에서 성잠시킨 GaN박막(HT-GaN) 위에 중간온도에서 성장된 GaN 에피층(IT-GaN)의 구조에 관한 연구가 선행되어야한다. 본 연구에서는 HT-GaN 위에 성장된 GaN 에피층에 미치는 성장 온도와 Si 도핑 효과에 관해 연구하였다.