- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Faceting and metal-exchange catalysis in (010) β-Ga <sub/>2</sub> O <sub/>3</sub> thin films homoepitaxially grown by plasma-assisted molecular beam epitaxy
摘要： We here present an experimental study on (010)-oriented β-Ga2O3 thin films homoepitaxially grown by plasma assisted molecular beam epitaxy. We study the effect of substrate treatments (i.e., O-plasma and Ga-etching) and several deposition parameters (i.e., growth temperature and metal-to-oxygen flux ratio) on the resulting Ga2O3 surface morphology and growth rate. In situ and ex-situ characterizations identified the formation of (110) and (ˉ110)-facets on the nominally oriented (010) surface induced by the Ga-etching of the substrate and by several growth conditions, suggesting (110) to be a stable (yet unexplored) substrate orientation. Moreover, we demonstrate how metal-exchange catalysis enabled by an additional In-flux significantly increases the growth rate (>threefold increment) of monoclinic Ga2O3 at high growth temperatures, while maintaining a low surface roughness (rms < 0.5 nm) and preventing the incorporation of In into the deposited layer. This study gives important indications for obtaining device-quality thin films and opens up the possibility to enhance the growth rate in β-Ga2O3 homoepitaxy on different surfaces [e.g., (100) and (001)] via molecular beam epitaxy.
关键词： molecular beam epitaxy,metal-exchange catalysis,surface morphology,homoepitaxy,β-Ga2O3
更新于2025-09-04 15:30:14
-
Features of the Initial Stage of GaN Growth on Si(111) Substrates by Nitrogen-Plasma-Assisted Molecular-Beam Epitaxy
摘要： The results of investigations of the effect of the initial conditions (nitridation of the Si(111) substrate, the GaN growth temperature, and the stoichiometry of GaN growth) on the growth kinetics and the GaN/Si(111)-layer polarity under nitrogen-plasma-assisted molecular-beam epitaxy are presented. It is experimentally established that the optimal initial condition for GaN epitaxy on Si(111) substrates is high-temperature nitridation of the Si(111) substrate carried out immediately before GaN growth. It is shown that it is possible to control the polarity of GaN by means of appropriate choice of the growth under conditions with N or Ga enrichment at the initial stage of GaN/Si(111) epitaxy.
关键词： GaN,polarity,Si(111),nitridation,molecular-beam epitaxy
更新于2025-09-04 15:30:14
-
Low-temperature homoepitaxial growth of two-dimensional antimony superlattices in silicon
摘要： The authors present a low-temperature process for the homoepitaxial growth of antimony superlattices in silicon. The all low-temperature superlattice doping process is compatible as a postfabrication step for device passivation. The authors have used low-temperature molecular beam epitaxy to embed atomically thin (2D), highly concentrated layers of dopant atoms within nanometers of the surface. This process allows for dopant densities on the order of 1013–1014 cm?2 (1020–1021 cm?3); higher than can be achieved with three-dimensional doping techniques. This effort builds on prior work with n-type delta doping; the authors have optimized the growth processes to achieve delta layers with sharp dopant profiles. By transitioning from a standard effusion cell to a valved cracker cell for antimony evaporation, the authors have achieved carrier densities approaching 1021 cm?3 with peak distribution at ～10 ? FWHM for single delta layers. Even at the highest dopant concentrations studied, no deterioration in carrier mobility is observed, suggesting the upper limit for dopant incorporation and activation has not yet been met. The authors will discuss the details related to growth optimization and show results from in situ monitoring by electron diffraction. They will also report on elemental and electrical characterization of the films.
关键词： silicon,molecular beam epitaxy,surface passivation,homoepitaxial growth,delta doping,low-temperature,antimony superlattices
更新于2025-09-04 15:30:14
-
Influence of Boron Antisite Defects on the Electrical Properties of MBE‐Grown GaAs Nanowires
摘要： Nanowires provide a platform for the integration of heterogeneous materials in III–V systems grown on Si. BxGa1(cid:1)xAs is an interesting material for strain applications, which has not yet been studied in nanowire form. The incorporation of boron in GaAs nanowires is investigated via DC-IV measurements. In transmission electron microscopy analysis a high concentration of boron is found at the nanowire edges, indicating surface segregation during growth. Nanowires grown under boron flux are found to exhibit Ohmic contacts and low contact resistances with p-type metallizations such as Au/Zn/Au or Cr/Au. Back-gated measurements confirmed the p-type behavior of such nanowires, indicating that boron is incorporated on antisite defects where it acts as a doubly-charged acceptor. This offers a new route for the inclusion of p-doped layers in GaAs-based nanowire heterostructures and the subsequent formation of Ohmic contacts.
关键词： boron doping,B:GaAs,nanowires,molecular beam epitaxy
更新于2025-09-04 15:30:14
-
Mg induced compositional change in InGaN alloys
摘要： Tunnel junctions are indispensable elements of multi-junction solar cells. The fabrication of InGaN tunnel junctions requires the growth of degenerately doped n- and p-type layers. While highly doped n-type InGaN films have been demonstrated, the growth of degenerately p-doped InGaN films and the fabrication of high indium fraction InGaN tunnel junctions is still to be demonstrated. We present an investigation of the effect of Mg doping on the InGaN crystal properties over a large range of Mg fluxes and InN mole fractions in the range from 30% to 40%, using multiple characterization techniques. InGaN thin films were grown on GaN/sapphire templates and doped with Mg using plasma assisted molecular beam epitaxy (PAMBE). We have found that the Mg concentration in the film increases linearly with the Mg beam equivalent pressure (BEP) at first, followed by a saturation at ~4x1021 cm-3 similar to the Mg doping behavior reported for GaN. The growth rate of the alloy changes by more than 50% with the changes in the surface availability of Mg. These effects can be explained through the saturation of the atomic sites available for incorporation in the case of Mg concentration saturation and by the passivation of the free nitrogen radicals in the case of the growth rate variation. The incorporation of In and Ga depends on the flux ratio (ΦIn + ΦGa) /(ΦMg) at the growth surface and it is shown that the decrease of this ratio below a threshold of ~2000 causes the almost complete loss of In and the formation of a new quaternary wide band gap semiconductor alloy (InGaMg)N.
关键词： In incorporation,(InGaMg)N alloy,Plasma-assisted molecular beam epitaxy,Tunnel junction,Mg-doped P-type InGaN,InGaN
更新于2025-09-04 15:30:14