Semiconductor Science Research Articles

Preface: phys. stat. sol. (b) 243/14

AbstractThe present special issue entitled Frontiers in Semiconductor Nanoscience has been prepared to honor Gerhard Abstreiter on the occasion of his 60th birthday and pay tribute to his long career, during which he has consistently operated at the frontiers in semiconductor physics and nanoscience. The twin issues in pss(a) and pss(b) consist of more than forty contributions from leading scientists in four of the general fields of semiconductor and nanostructure physics in which Gerhard has been most active: (i) quantum transport, (ii) optical properties and coherent phenomena, (iii) nano‐biological systems and (iv) novel materials and nanostructures. As discussed by Günther Bauer in his laudatio, Gerhard has consistently made highly significant contributions to each and every one of these fields throughout his career, often leading to new advances that have had a major impact in the fields of semiconductor nanostructures and condensed matter physics.In addition to providing a fitting tribute to Gerhard's long scientific career, we hope that this issue will stimulate imaginative exploitation of these emerging and rapidly developing fields. We are sure that all contributors, colleagues and collaborators join us in wishing Gerhard a very happy birthday and look forward to working on future problems in the science of semiconductors and their nanostructures. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Preface: phys. stat. sol. (a) 203/14

AbstractThe present special issue entitled Frontiers in Semiconductor Nanoscience has been prepared to honor Gerhard Abstreiter on the occasion of his 60th birthday and pay tribute to his long career, during which he has consistently operated at the frontiers in semiconductor physics and nanoscience. The twin issues in pss(a) and pss(b) consist of more than forty contributions from leading scientists in four of the general fields of semiconductor and nanostructure physics in which Gerhard has been most active: (i) quantum transport, (ii) optical properties and coherent phenomena, (iii) nano‐biological systems and (iv) novel materials and nanostructures. As discussed by Günther Bauer in his laudatio, Gerhard has consistently made highly significant contributions to each and every one of these fields throughout his career, often leading to new advances that have had a major impact in the fields of semiconductor nanostructures and condensed matter physics.In addition to providing a fitting tribute to Gerhard's long scientific career, we hope that this issue will stimulate imaginative exploitation of these emerging and rapidly developing fields. We are sure that all contributors, colleagues and collaborators join us in wishing Gerhard a very happy birthday and look forward to working on future problems in the science of semiconductors and their nanostructures. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Laudatio for Gerhard Abstreiter

Laudatio for Gerhard Abstreiter

Laudatio for Gerhard Abstreiter

Laudatio for Gerhard Abstreiter

Proceedings of the 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED‐2004)

The 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004) was held in Gyeongju, Korea, 15–19 March 2004. The purpose of the symposium was to provide a forum for scientists and engineers to discuss recent progress and future trends in the rapidly advancing wide band gap semiconductor science and technologies and their applications in blue laser and light emitting diodes.

First-principles materials study for spintronics: MnAs and MnN

We report ab-initio all electrons density- functional calculations for the electronic structure of the compounds MnAs and MnN, in the zinc-blende phase. They are potential materials for use in fabrication of new functional semiconductors taking advantage of the spin degree of freedom. The aim is the establishing of the semiconductor spin electronics (spintronics) as a practical technology [H. Ohno, Semiconductor Science and Technology 17, 4 (2002).]. We compare results obtained using the theoretical approaches LDA (Local Density Approximation) and GGA (Generalized Gradient Approximation). The calculations are spin-polarized and we follow the evolution of the band structures as a function of lattice parameter. We compare also the evolution of the density of states of the majority-spins and of the minority-spins. We conclude that, depending on the lattice parameter, both materials may be half-metallic, therefore showing conduction by charge carriers of one spin direction exclusively: the majority- spin band is continuous, while the minority-spin has a gap. Both materials reach a total magnetization of the order of 4 mB. MnN changes from paramagnetic to ferromagnetic with the increase of the lattice parameter.

Global existence and asymptotic behavior to the solutions of 1-D Lyumkis energy transport model for semiconductors

The global existence and asymptotic behavior of smooth solutions to the initial-boundary value problem for the 1-D Lyumkis energy transport model in semiconductor science is studied. When the boundary is insulated, the smooth solution of the problem converges to a stationary solution of the drift diffusion equations, exponentially fast as t → ∞ t \to \infty .

The solution of Lyumkis energy transport model in semiconductor science

AbstractThe existence and uniqueness of $ (W_{\hskip -3.5pt p}^{2,1}(Q_{\tau}))^{2}\times L_{q}(0,\tau;W_{\hskip -2.5pt q}^{1}(\Omega))$ solution to Lyumkis energy transport model is discussed for N+2<p≤q<∞ and 1≤N≤3. Copyright © 2003 John Wiley & Sons, Ltd.

First observation of SiO2/Si(100) interfaces by spherical aberration-corrected high-resolution transmission electron microscopy.

SiO2/Si(100) interfaces were for the first time observed by a spherical aberration-corrected high-resolution transmission electron microscope in a cross-sectional mode. As the Fresnel fringes were not contrasted at the interfaces, the interfacial structures were clearly observed without the need for artificial image contrast. Atomic steps and defects on the Si(100) surfaces were accurately identified. Also, image simulations with the target imaging performance revealed oxygen atomic columns between silicon-silicon bonds. The present instrument is of potential use for semiconductor science and technology, even for the analysis of oxygen atoms at interfaces.

Wafer-scale strain engineering on silicon for fabrication of ultimately controlled nanostructures

We propose a method of strain distribution control on planar Si(001) and Si(111) wafers for nanostructure self-assembly, taking a long-term view toward future Si semiconductor science and technology. Oxygen ions are implanted through patterned layers on the Si wafers. The sample is then annealed at 1325 \ifmmode^\circ\else\textdegree\fi{}C to produce bulk oxide inclusions that yield a tensile and/or compressive strain distribution on the silicon surface. We also demonstrate that strained epitaxial growth of Ge on the Si(001) substrate surface at 550 \ifmmode^\circ\else\textdegree\fi{}C in an ultrahigh vacuum produces three-dimensional islands whose location and size distribution are well controlled. The degree of localization control is in agreement with simulations of the elastic strain distribution. Additionally, we show that increasing the Ge growth temperature 50 \ifmmode^\circ\else\textdegree\fi{}C significantly reduces the density of stray dots that randomly grow on the Si surface. The samples were observed by atomic force microscopy and cross-sectional transmission electron microscopy. Strains on the silicon surface, produced by the buried silicon oxides, were measured by micro-Raman spectroscopy.

Proceedings of the Tenth International Conference on High Pressure Semiconductor Physics (HPSP‐X)

AbstractThe Tenth International Conference on High Pressure Semiconductor Physics (HPSP‐X) was held as a satellite meeting of the International Conference on the Physics of Semiconductors in Guildford from 5 to 8 August 2002. It brought together scientists and engineers who use high pressure to study the science and technology of semiconductors. The HPSP‐X conference reviewed the latest issues and developments in the physics of both bulk and low‐dimensional semiconductor materials and devices under pressure. It covered all aspects of fundamental and applied high‐pressure semiconductor research, including experimental and theoretical investigations under isotropic or anisotropic stress conditions. Topics such as electronic structures, vibrational and optical properties, transport phenomena, defect states, phase transitions, and novel materials or structures are included in this issue.Following the meetings HPSP‐VII in Schwäbisch Gmünd, phys. stat. sol. (b) 198, No. 1 (1996); HPSP‐VIII in Thessaloniki, phys. stat. sol. (b) 211, No. 1 (1998), and HPSP‐IX in Sapporo, phys. stat. sol. (b) 223, No. 1/2 (2001), the proceedings of this successful conference series are published in physica status solidi for the fourth time.

William Paul: a scientist, a teacher, and a friend

AbstractThe author belongs to the first generation of graduate students Bill Paul supervised at Harvard. He learned from Bill the physics of semiconductors, especially under high pressure, and also how to manage a research group. Last, but not least, he also learned from him the rules of ethics of the scientific endeavor which seem to be often forgotten in recent times. The “Bill Paul Experience” left a permanent imprint on the speaker's future career. After a short biographical sketch, the article discusses the scientific lineage of Bill Paul and presents a bibliometric analysis of his publications. This is followed by a discussion of what the speaker and the Institute of Scientific Information (ISI) believe are Bill's most important contributions to Semiconductor Science, in particular the application of high pressure to the investigation of the band structure of semiconductors and the wide field of amorphous materials.

Strong Solutions to a Kind of Cross Diffusion Parabolic System

A kind of strongly coupled cross diffusion parabolic system, which can be used as the energy transport model in semiconductor science, is studied in this paper. The existence and uniqueness of strong solution to the initial boundary value problem are obtained, under the condition that the initial data are a small perturbation of an isothermal stationary solution. Based on this result, an application of Newton iteration on solving this problem is also given. In the last decades, more and more strongly coupled parabolic systems with (de- generate or non-degenerate) cross diffusion terms were derived from applied science, for instance, chemotaxis phenomenon in biomathematics, generalized drift diffusion and energy transport model in semiconductor science, separation of granular material, etc. In real applications, due to more information included, such kinds of cross diffu- sion models describe the phenomena more clearly than the classical weakly coupled diffusion systems. But very few theoretical results have been obtained up to now. In the present paper, we consider the following cross diffusion parabolic system.

Current status of research and development of III–N–V semiconductor alloys

In this topical issue of Semiconductor Science and Technology, 18 invited papers have been devoted to reviewing the current status of research and development in III–N–V semiconductor alloys. Leading researchers in this field discuss the growth and processing, experimental characterization, theoretical understanding, and device design and fabrication of this recently developed class of semiconductor alloys.

Surface/interface issues in THz electronics

Basic THz elements are produced by standard semiconductor science and technology. Therefore, three main material systems are used. These are first of all semiconductors, for active and passive layer formation; metals, for interconnect and contact formation; and insulators, for passivation and isolation purposes. Additionally, these materials are structured in order to produce a device with desired dimensions and characteristics. Semiconductor surfaces, in particular suffer considerable changes during technological processing. Thus, surface and interface issues are essential here to be considered. Semiconductor–dielectric, semiconductor–metal, and semiconductor–semiconductor interfaces as well as surface effects for the case of GaAs are discussed in detail from the point of view of Schottky diodes and heterostructure-based devices for THz applications.

A novel technique to grow Ge quantum dots on porous Si by ultrahigh vacuum chemical vapor deposition

Semiconductor quantum dots have attracted worldwide attention now due to their suitability for quantum physics study and their potential device applications in both future microelectronics and optoelectronics industry. Ge and SiGe quantum dots with their technological compatibility to the Si industry are especially important [1, 2]. Recent research in this field led to very promising results, such as the efficient Si-SiGe dry etched quantum dot based light emitting diodes, which could potentially be used in all Si-based optical interconnects on Si microchips. The investigation on semiconductor quantum dots is one of the most attractive areas in semiconductor science and technology. A variety of techniques have been developed to fabricate semiconductor quantum dots [3–13], among them the self-assembled growth of nanometer size islands in highly strained system is one of the methods on which people’s interests are currently focused. Ge/Si is also a strain system with the misfit in the lattice constant of 4.2%. Several groups have achieved the self-organizing growth of Ge-rich islands on Si by using molecular beam epitaxy or chemical vapor deposition. However, it is very difficult to control the size and position, To overcome this difficulty and to accurately control dots in both size and position, certain methods have been proposed. One of them is to define SiGe/Si quantum dots by electron beam lithography and reactive ion etching after growing quantum well structure. Another method is to grow dots in the Stranski-Krastanov mode on cleaved edges utilizing the periodic strain modulation resulting from the underlying SiGe/Si multiple quantum wells. A method considered to be more effective is to fabricate dots in selective areas on patterned substrates. By using selective epitaxial growth on patterned substrate, it is generally possible to control the size and the position. Here, we used a very low cost way to grow Ge quantum dots on porous silicon, substituting for a patterned substrate, as its substrate successfully. In this work, the Ge dots were grown via an ultrahigh vacuum chemical vapor deposition (UHV/CVD) system, although can be done by molecular beam epitaxy and other techniques. The porous silicon is formed by anodic dissolution of crystalline silicon in 50% hydrofluoric acid solution diluted by alcohol with the equipment shown in Fig. 1. The wafers were diameter 75 mm Czochralski silicon with 〈100〉 orientation, p-type (boron doped, 10 cm). Before anodization, aluminum alloy layers were formed on the back of silicon wafers as the low resistivity contact layer in order to make the anodic current distribution uniform. We know that the density and size of porous silicon are affected mainly by silicon resistivity, current density, hydrofluoric acid concentration, and etching time [14, 15]. The uniform and quantum size porous silicon was obtained with 5 mA/cm2 current density and 5 min etching time. Sample was grown by a UHV/CVD system. Reactants were high pure germane (GeH4). The pressure during film growth was in the range of 5–10 mTorr. Prior to being introduced into the sample chamber, the porous silicon wafer was submitted to a chemical cleaning process, followed by a dip in dilute hydrofluoric acid (10% HF) without being rinsed. After being transferred to the growth chamber, the substrate was baked at 720 ◦C in the 5 sccm flow GeH4 environment for 5 min. This process had two results: one was to remove residue oxygen [16], the other was to deposit Ge islands uniformly. The size of Ge islands grown on the porous silicon was small than that of Si substrate. The structure of Ge dots on porous silicon was characterized by a Philip X’pert X-ray diffraction (XRD). The surface morphology and the dots’ dimension were investigated by atomic force microscopy (AFM). Photoluminescence (PL) spectra were measured in standard lock-in configuration with a He-Ne laser for exciton and with a liquid-nitrogen cooled Ge detector. Fig. 2 shows the measured X-ray diffraction rocking curve of the sample of Ge quantum dots on porous silicon. We can see that the dominant peak at 2θ = 69.12 ◦ (peak 1, plane space d1 = 1.363 A) is the (400) diffraction from Si substrate and peak 2 is due to Cu Kα2 line from the Si substrate. The peak 3 at 2θ = 68.87 ◦ (plane space d3 = 1.368 A) is identified as the porous silicon diffraction. The lattice parameter of the porous silicon layer is a little bigger than that of silicon. Therefore, porosity affects the crystal lattice by producing a

Comment on `Modelling the optical constants of GaAs:excitonic effects at E1,E1 + Δ1 criticalpoints'

Djurisic and Li (1999, Semiconductor Science andTechnology 14 958) have recently presented acalculation of the optical constants of GaAs in which they donot take into account excitonic effects at either E1,E1 + Δ1 or E0,E0 + Δ0 critical points (CPs).They employ band-to-band single-particle expressions withan energy-dependent pseudo-Gaussian broadening function.Their paper states that including excitonic effects at theformer CPs has `dubious physical interpretation'. It is alsoclaimed that (a) `excitonic effects are usually more pronouncedat E0,E0 + Δ0 than at the E1,E1 + Δ1 CPs',(b) `at room temperature the excitons are severelybroadened and should not contributesignificantly to the dielectric function' and (c) `excitoniceffects at E1,E1 + Δ1 critical points do not represent asignificant contribution to the dielectric function at roomtemperature for materials with low exciton binding energy'.These statements are completely incorrect, as is their fittingscheme.

Innovative Curriculum on Electronic Materials Processing and Engingeering

Recognizing that the traditional engineering education training is often inadequate in preparing the students for the challanges presented by this industry's dynamic environment and insufficient to meet the empoyer's criteria in hiring new engineers, a new curriculum on Semiconductor Manufacturing is instituted in the Chemical Engineering Department at UCLA to train the students in various scientific and technologica areas that are pertinenet to the microelectronics industries. This paper describes this new mutidisciplinary curriculum that provides knowledge and skills in semiconductor manufacturing through a series ofcourses that emphasize on the application of fundamenta engineeering disciplines in solid-state physics, materials science of semiconductors, and chemical processing. The curriculum comprises three major components:(1)a comprehensive course curriculum in semiconductor manufacturing; (2) a laboratory for hands-on training in semiconductor device fabrication; (3) design of experiments. The capstone laboratory course is designed to strengthen students’ training in “unit operatins” used in semicounductor manufacturing and allow them to practice engineering principles using the state-of-the-art experimental setup. It comprises the most comprehensive training(seven photolithographic steps and numero0us chemical processes)in fabricating and testing complementary metal-oxide-semiconductor (CMOS) devices. This curriculum is recentyaccredited by the Accreditation Board for Engineering and Technology(ABET).

Quantum electronics: the physics and technology of low-dimensional electronic systems into the new millennium

In 1947, a research team at the Bell Telephone Laboratories in New Jersey demonstrated a new electrical amplifier, the ‘transistor’. Unlike the prevailing vacuum–tube amplifiers, the transistor was a solid–state device built from a piece of semiconductor crystal. Its invention sparked a revolution in electronics and communication technology that continues to rage unabated 50 years later. But one of the most striking aspects of the progress of semiconductor science over the last 50 years is how the commercially driven technological developments in semiconductor devices have occurred alongside advances in fundamental physics obtained from investigation of the same semiconductor devices. The basic building blocks of computer and communication technologies are perfect for the study of electrons and their interactions with each other and with their environment; the fundamental interactions of one of nature9most fundamental particles. This paper develops the symbiotic relationship between the technological and the fundamental aspects of these electronic systems and reviews recent highlights of semiconductor physics and technology. I will also look, however, at a future generation of microelectronic devices in which the fusion of molecular biology, chemistry and physics will produce breathtaking results.

Elastic mid-infrared light scattering: A basis for microscopy of large-scale electrically active defects in semiconducting materials

A method of the mid-IR-laser microscopy has been recently proposed for the investigation of the large-scale electrically and recombination active defects in semiconductors and nondestructive inspection of semiconductor materials and structures in the industries of microelectronics and photovoltaics. The basis for this development was laid with a wide cycle of the investigations on the low-angle mid-IR-light scattering in semiconductors. The essence of the technical idea was to apply the dark-field method for spatial filtering of the scattered light in the scanning mid-IR-laser microscope. This approach enabled the visualization of large-scale electrically active defects which are the regions enriched with ionized electrically active centers. The photoexcitation of excess carriers within a small volume located in the probe mid-IR-laser beam enabled the visualization of the large-scale recombination-active defects like those revealed in the optical or electron beam induced current methods. Both these methods of the scanning mid-IR-laser microscopy are now introduced in detail in the present article as well as a summary of techniques used in the standard method of the low-angle mid-IR-light scattering itself. Besides the techniques for direct observations, methods for analyses of the defect composition associated with the mid-IR-laser microscopy are also discussed in the article. Special attention is paid upon potential applications of the above methods as characterization and testing techniques in the semiconductor science and industry. It is concluded that elastic midinfrared laser light scattering is a basis for the development of a variety of research techniques and instruments which could be useful in different branches of basic and applied research work in the field of defect engineered semiconductors as well as for the development of devices for quality inspections in the semiconductor industry. Being contactless, nondestructive and nonpolluting, techniques based on midinfrared light scattering could also find many applications for automation of the technological process control as well as the process remote monitoring.