The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

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Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD

Nanomaterials ◽

10.3390/nano11040928 ◽

2021 ◽

Vol 11 (4) ◽

pp. 928

Author(s):

Yong Du ◽

Zhenzhen Kong ◽

Muhammet Toprak ◽

Guilei Wang ◽

Yuanhao Miao ◽

...

Keyword(s):

High Temperature ◽

Buffer Layer ◽

Layer Thickness ◽

Growth Temperature ◽

Crystalline Quality ◽

Initial Growth ◽

Two Dimensional ◽

High Quality ◽

Reduced Pressure

This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski–Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it’s threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 °C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 × 107 cm−2). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.

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Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088816 ◽

1991 ◽

Vol 49 ◽

pp. 900-901 ◽

Cited By ~ 1

Author(s):

Alain Claverie ◽

Zuzanna Liliental-Weber

Keyword(s):

Transport Properties ◽

Layer Thickness ◽

Growth Temperature ◽

Low Temperatures ◽

Lattice Parameter ◽

Crystalline Quality ◽

Insulating Properties ◽

Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

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Effect of low-temperature GaN buffer layer on the crystalline quality of subsequent GaN layers grown by MOVPE

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2006.10.189 ◽

2007 ◽

Vol 298 ◽

pp. 232-234 ◽

Cited By ~ 21

Author(s):

K. Hoshino ◽

N. Yanagita ◽

M. Araki ◽

K. Tadatomo

Keyword(s):

Low Temperature ◽

Buffer Layer ◽

Crystalline Quality ◽

Gan Buffer Layer

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Influence of buffer layer thickness and epilayer’s growth temperature on crystalline quality of InAs0.6P0.4/InP grown by LP-MOCVD

Solid State Communications ◽

10.1016/j.ssc.2011.03.027 ◽

2011 ◽

Vol 151 (12) ◽

pp. 904-907 ◽

Cited By ~ 3

Author(s):

Xia Liu ◽

Hang Song ◽

Guoqing Miao ◽

Hong Jiang ◽

Lianzhen Cao ◽

...

Keyword(s):

Buffer Layer ◽

Layer Thickness ◽

Growth Temperature ◽

Crystalline Quality ◽

Buffer Layer Thickness

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Effects of the Nitridation Process of (0001) Sapphire on Crystalline Quality of InN Grown by RF-MBE

MRS Proceedings ◽

10.1557/proc-831-e4.2 ◽

2004 ◽

Vol 831 ◽

Cited By ~ 4

Author(s):

Daisuke Muto ◽

Ryotaro Yoneda ◽

Hiroyuki Naoi ◽

Masahito Kurouchi ◽

Tsutomu Araki ◽

...

Keyword(s):

Low Temperature ◽

Buffer Layer ◽

Buffer Layers ◽

Crystalline Quality ◽

Constant Independent ◽

Nitrogen Flux ◽

Sapphire Substrates ◽

Nitridation Process ◽

Flux Modulation

ABSTRACTThe effects of the nitridation process of (0001) sapphire on crystalline quality of InN were clearly demonstrated. The InN films were grown on NFM (nitrogen flux modulation) HT-InN or LT-InN buffer layers, which had been deposited on nitridated sapphire substrates. We found that low-temperature nitridation of sapphire is effective in improving the tilt distribution of InN films. Whereas the twist distribution remained narrow and almost constant, independent of nitridation conditions, when LT-InN buffer layers were used. The XRC-FWHM value of 54 arcsec for (0002) InN, the lowest reported to date, was achieved by using the LT-InN buffer layer and sapphire nitridation at 300°C for 3 hours.

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Optimisation Of The Heteroepitaxy Of Ge On GaAs For Minority-Carrier Lifetime

MRS Proceedings ◽

10.1557/proc-198-253 ◽

1990 ◽

Vol 198 ◽

Cited By ~ 1

Author(s):

R. Venkatasubramanian ◽

M.L. Timmons ◽

S. Bothra ◽

J.M. Borrego

Keyword(s):

High Temperature ◽

Buffer Layer ◽

Gaas Substrate ◽

Carrier Lifetime ◽

Minority Carrier ◽

High Growth ◽

Minority Carrier Lifetime ◽

Layer Growth ◽

Buffer Layers ◽

Temperature Growth

ABSTRACTGrowth of Ge on GaAs at reasonably high temperatures, which produce better crystallinity in the Ge, presents serious difficulties due to the dissociation of the GaAs substrate. In this paper, we describe the growth of a lowtemperature buffer layer of Ge on GaAs that prevents decomposition of the GaAs during high-temperature growth of Ge. Using this approach, we present the first report of highly specular, mass-transport-limited high-temperature growth of Ge on GaAs that is comparable to the homoepitaxy of Ge. The factors affecting the minority-carrier lifetime of Ge on GaAs, using such an epitaxial growth technique, were studied with a non-invasive microwave technique. Lifetime variations, from very low values to about 0.45 μsec, were obtained as a function of the growth conditions. Significantly, the removal of the surface oxide on the GaAs substrate prior to low-temperature buffer-layer growth, terminating the flow of germane(GeH4) during the ramp to high growth temperatures, thinner buffer layers, and high-temperature growth of Ge were found to be important for obtaining long lifetimes.

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Strained Si0.2Ge0.8/Ge multilayer Stacks Epitaxially Grown on a Low-/High-Temperature Ge Buffer Layer and Selective Wet-Etching of Germanium

Nanomaterials ◽

10.3390/nano10091715 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1715

Author(s):

Lu Xie ◽

Huilong Zhu ◽

Yongkui Zhang ◽

Xuezheng Ai ◽

Guilei Wang ◽

...

Keyword(s):

High Temperature ◽

Buffer Layer ◽

Wet Etching ◽

Short Channel ◽

Reduced Pressure ◽

Temperature Growth ◽

Vapor Deposition Technique ◽

H2o2 Solution ◽

The Impact

With the development of new designs and materials for nano-scale transistors, vertical Gate-All-Around Field Effect Transistors (vGAAFETs) with germanium as channel materials have emerged as excellent choices. The driving forces for this choice are the full control of the short channel effect and the high carrier mobility in the channel region. In this work, a novel process to form the structure for a VGAA transistor with a Ge channel is presented. The structure consists of multilayers of Si0.2Ge0.8/Ge grown on a Ge buffer layer grown by the reduced pressure chemical vapor deposition technique. The Ge buffer layer growth consists of low-temperature growth at 400 °C and high-temperature growth at 650 °C. The impact of the epitaxial quality of the Ge buffer on the defect density in the Si0.2Ge0.8/Ge stack has been studied. In this part, different thicknesses (0.6, 1.2 and 2.0 µm) of the Ge buffer on the quality of the Si0.2Ge0.8/Ge stack structure have been investigated. The thicker Ge buffer layer can improve surface roughness. A high-quality and atomically smooth surface with RMS 0.73 nm of the Si0.2Ge0.8/Ge stack structure can be successfully realized on the 1.2 µm Ge buffer layer. After the epitaxy step, the multilayer is vertically dry-etched to form a fin where the Ge channel is selectively released to SiGe by using wet-etching in HNO3 and H2O2 solution at room temperature. It has been found that the solution concentration has a great effect on the etch rate. The relative etching depth of Ge is linearly dependent on the etching time in H2O2 solution. The results of this study emphasize the selective etching of germanium and provide the experimental basis for the release of germanium channels in the future.

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Characteristics of Polycrystalline 3C-SiC Thin Films Grown on AlN Buffer Layer by CVD

Materials Science Forum ◽

10.4028/www.scientific.net/msf.600-603.255 ◽

2008 ◽

Vol 600-603 ◽

pp. 255-258

Author(s):

Gwiy Sang Chung ◽

Kang San Kim

Keyword(s):

Buffer Layer ◽

Growth Temperature ◽

Electron Mobility ◽

Crystalline Quality ◽

Chemical Compositions ◽

Suitable Material ◽

Bonding Structure ◽

Ft Ir ◽

Aln Buffer

This paper describes the characteristics of poly (Polycrystalline) 3C-SiC grown on SiO2 and AlN buffers, respectively. The crystallinity and the bonding structure of poly 3C-SiC grown on each buffer layer were investigated according to various growth temperatures. The crystalline quality of poly 3C-SiC was improved from resulting in decrease of FWHM (Full width half maximum) of XRD and FT-IR by increasing the growth temperature. The minimum growth temperature of poly 3C-SiC was 1100 °C. The surface chemical composition and the electron mobility of poly 3C-SiC grown on each buffer layer were investigated by XPS and Hall Effect. The chemical compositions of surface of poly 3C-SiC grown on SiO2 and AlN were not different. However, their electron mobilities were 7.65 ㎝2/V.s and 14.8 ㎝2/V.s, respectively. Therefore, since the electron mobility of 3C-SiC/AlN was two times higher than that of 3C-SiC/SiO2, AlN is a suitable material, as buffer layer, for SiC growth with excellent crystalline quality.

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Study of the growth mechanism and properties of InN films grown by MOCVD

MRS Proceedings ◽

10.1557/proc-798-y12.8 ◽

2003 ◽

Vol 798 ◽

Cited By ~ 3

Author(s):

Abhishek Jain ◽

Joan M. Redwing

Keyword(s):

Thin Films ◽

Buffer Layer ◽

Growth Temperature ◽

Room Temperature ◽

Growth Conditions ◽

Buffer Layers ◽

Film Morphology ◽

Buffer Layer Thickness ◽

Aln Buffer

ABSTRACTThin films of InN were grown on (0001) Sapphire by MOCVD. The effect of growth conditions and buffer layer on the film morphology was studied. Growth temperature and TMI flow rate were important factors in the growth of InN. The use of a low temperature AlN buffer layer was also found to improve the morphology and crystal quality of the films. Thin (<40Å) AlN buffer layers produced the best results while polycrystalline InN was obtained when the buffer layer thickness exceeded 60Å. Delamination of the InN films was observed to occur at growth temperature, which limited the thickness of the films to less than 300 nm. A room temperature mobility of 792 cm2/Vs and an electron concentration of 2.1×1019 cm-3 were measured in an approximately 200 nm thick InN layer grown on sapphire.

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