Ge Segregation and Surface Roughening During Si Growth on Ge(001)2×l by Gas-Source Molecular Beam Epitaxy from Si2H6

1992 ◽  
Vol 280 ◽  
Author(s):  
R. Tsu ◽  
D.-S. Lin ◽  
J. E. Greene ◽  
T.-C. Chiang
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Three Dimensional ◽  
High Energy ◽  
Single Step ◽  
Scanning Tunneling ◽  
Island Growth ◽  
Tunneling Microscopy ◽  
Compositional Evolution ◽  
Gas Source

ABSTRACTSurface morphological and compositional evolution during the initial stages of Si growth on Ge(001)2×1 by cyclic gas-source molecular-beam epitaxy (GSMBE) from Si2H6 has been investigated using in-situ reflection high-energy electron diffraction (RHEED), Auger electron spectroscopy (AES), electron energy-loss spectroscopy (EELS), and scanning tunneling microscopy (STM). At 550 °C, single-step-height island growth was observed for nominal Si deposition thicknesses tsi up to ≃ 1.5 ML. The islands were essentially pure Ge which segregated to the surface as H was desorbed. At higher tsi, the Ge coverage decreased, the surface roughened, and two-dimensional multi-layer island growth was observed for tSi up to ≃8 ML above which three-dimensional island growth was obtained. For thick layers (t S: 75 ML), no Ge was detected at the surface.

Growth of Si on Ge(001)2×l by gas-source molecular beam epitaxy

1993 ◽  
Vol 51 ◽  
pp. 806-807
Author(s):  
H.Z. Xiao ◽  
R. Tsu ◽  
I.M. Robertson ◽  
H.K. Birnbaum ◽  
J.E. Greene
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
High Energy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Gas Source ◽  
High Quality Result ◽  
Strained Layer Superlattices

The growth of SiGe strained-layer superlattices (SLS) has been received considerable attention due to the electronic and optoelectronic properties of these layers. In addition, these structures offer tantalizing possibilities for "band gap engineering" through the use of strain and chemically ordered alloys. The remaining barriers to grow the SiGe SLS structures with high quality result from the generation of large densities of defects, such as dislocations, twins, stacking faults, etc., at the heterointerfaces arising from the misfit strain relaxation. Other problems associated with the growth of the SiGe SLS structures are segregation and low incorporation of the dopants and inter-diffusion of Si and Ge. In the present study, the inter-mixing of Si and Ge and the generation of the defects in Si epilayers grown on Ge(001)2×1 at 550 °C by gas-source molecular beam epitaxy (MBE) from Si2H6 were studied using transmission electron microscopy (TEM), in-situ reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM) and electron energy-loss spectroscopy (EELS).

Gas Source Molecular Beam Epitaxy Growth of GaN-Rich Side of GaNP Alloys and Their Observation by Scanning Tunneling Microscopy

1997 ◽  
Vol 36 (Part 1, No. 6B) ◽  
pp. 3810-3813 ◽  
Author(s):  
Reiko Kuroiwa ◽  
Hajime Asahi ◽  
Kakuya Iwata ◽  
Seong-Jin Kim ◽  
Joo-Hyong Noh ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Scanning Tunneling ◽  
Molecular Beam Epitaxy Growth ◽  
Tunneling Microscopy ◽  
Gas Source ◽  
Rich Side

Growth of Laser Ablated YBa2Cu3O7−δ Films as Examined by Rheed and Scanning Tunneling Microscopy

1992 ◽  
Vol 285 ◽  
Author(s):  
Stephen E. Russek ◽  
Alexana Roshko ◽  
Steven C. Sanders ◽  
David A. Rudman ◽  
J. W. Ekin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Three Dimensional ◽  
High Energy ◽  
Spiral Growth ◽  
Scanning Tunneling ◽  
Initial Growth ◽  
Rheed Pattern ◽  
Island Growth ◽  
Tunneling Microscopy

ABSTRACTUsing scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED) we have examined the growth morphology, surface structure, and surface degradation of laser ablated YBa2Cu3O7−δ thin films. Films from 5 nm to ltm thick were studied. The films were deposited on MgO and LaAlO3 substrates using two different excimer laser ablation systems. Both island nucleated and spiral growth morphologies were observed depending on the substrate material and deposition rate used. The initial growth mechanism observed for a 5–10 nm thick film is replicated through different growth layers up to thicknesses of 200 run. Beyond 200 rnm, the films show some a-axis grains and other outgrowths. The thinnest films (5–10 nm) show considerable surface roughness on the order of 3–4 nm. For both growth mechanisms the ledge width remains approximately constant (∼ 30 nm) and the surface roughness increases as the film thickness increases. The films with spiral growth have streaked RHEED patterns despite having considerable surface roughness, while the films with island growth have more of a three dimensional diffraction pattern. RHEED patterns were obtained after the film surfaces were degraded by exposure to air, KOH developer, a Br-methanol etch, and a shallow ion mill. Exposure to air and KOH developer caused only moderate degradation of the RHEED pattern whereas a shallow (I nm deep) 300 V ion mill completely destroyed the RHEED pattern.

Direct Observations of the Strain-Limited Island Growth of Sn-Doped GaAs(100)

1998 ◽  
Vol 05 (03n04) ◽  
pp. 783-795 ◽  
Author(s):  
A. M. Dabiran ◽  
S. M. Seutter ◽  
P. I. Cohen
Keyword(s):  
Native Species ◽  
Surface Segregation ◽  
High Surface ◽  
Three Dimensional ◽  
High Energy ◽  
Layer Growth ◽  
Scanning Tunneling ◽  
Layer By Layer ◽  
Island Growth ◽  
Tunneling Microscopy

We have used scanning tunneling microscopy (STM) in ultrahigh vacuum and atomic force microscopy (AFM) in air to investigate the microscopic mechanisms of Sn surface segregation during the molecular beam epitaxial growth of GaAs and AlAs(100). Submonolayer amounts of Sn segregate to the surface during growth and strongly modify the growth kinetics. This is indicated by both extra-ordinary reflection high energy electron diffraction (RHEED) measurements, and the STM and AFM images of rapidly quenched growth fronts. At the high surface coverages of 0.1–0.6 monolayers of Sn, studied in this work, neither step bunching nor three-dimensional (3D) growth of GaAs(100), was observed. Instead, STM and RHEED measurements indicated a significantly enhanced layer-by-layer growth of GaAs with increasing surface coverage of Sn. STM snapshots of the initial stages of GaAs growth revealed 2D islands which contained a higher-than-equilibrium bulk concentration of Sn, in Ga-substitutional sites, of up to 50%. Other directly observed Sn effects which are presented in this work include the removal of GaAs(100) island growth anisotropy and the formation of 2D islands with a relatively narrow distribution of size and separation. The completion of the top layers is shown to proceed by the coalescence of these islands before any significant nucleation of the next layer islands. This effect is used to explain the Sn enhancement of the layer-by-layer growth which was indicated in our RHEED and scanning probe observations. A model is presented for Sn segregation which explains these results based on an island-size-dependent, strain-driven, oscillatory Sn occupation of Ga-substitutional sites and surface interstitial sites on top GaAs(100) layers during growth. This model, which introduces a strain-limiting mechanism for the size and shape of the 2D islands, can also explain the observed enhancement of postgrowth surface recovery, as well as a delayed onset in increasing adatom surface diffusion length with increasing Sn coverage. The main conclusion is that, if impurity incorporation results in significant strain, then in addition to step climbing by surface impurities, the exchange of incorporated impurities with native species in top layers can be an important path for impurity segregation during expitaxial growth.

scholarly journals Scanning Tunneling Microscopy Studies of InGaN Growth by Molecular Beam Epitaxy

1999 ◽  
Vol 4 (S1) ◽  
pp. 858-863
Author(s):  
Huajie Chen ◽  
A. R. Smith ◽  
R. M. Feenstra ◽  
D. W. Greve ◽  
J. E. Northrup
Keyword(s):  
Molecular Beam Epitaxy ◽  
Scanning Tunneling Microscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Growth Parameters ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Group V ◽  
Group Iii ◽  
Ingan Alloys

InGaN alloys with indium compositions ranging from 0–40% have been grown by molecular beam epitaxy. The dependence of the indium incorporation on growth temperature and group III/group V ratio has been studied. Scanning tunneling microscopy images, interpreted using first-principles theoretical computations, show that there is strong indium surface segregation on InGaN. Based on this surface segregation, a qualitative model is proposed to explain the observed indium incorporation dependence on the growth parameters.

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