Index Semiconductor Research Articles

The Long-term Relationship between USD to CNY Exchange rate and China’s Semiconductor: An Empirical Research

As a fast-growing industry, semiconductors have gradually become a necessity in the modern world. In addition to its economic importance, the semiconductor industry is closely linked to national and social security. Modern national security largely depends on the level of science and technology, and the level of science and technology in the semiconductor industry plays a decisive role, so the development of the chip industry determines a country's national security and military status to a large extent. China, now the world's second largest economy, is also aggressively developing its semiconductor industry. Meanwhile, the import and export of the semiconductor industry is largely affected by the exchange rate between China and the United States. In this paper, China's semiconductor index from January 1994 to September 2022 and the USD to RMB exchange rate from January 1994 to present are extracted. The VAR model was applied in the study to evaluate the link between variables, and the ARMA-GARCH model was used to determine and analyze both earning ability and stock volatility throughout these years. The study predicts the future development direction of Chinese semiconductor industry and provides investment recommendations to its stakeholders.

On predicting the semiconductor industry cycle: a Bayesian model averaging approach

This study considers the model uncertainty and utilizes the Bayesian model averaging (BMA) approach to identify useful predictors of the semiconductor industry cycle from a list of 70 potential predictors. The posterior inclusion probabilities, posterior means, and posterior standard deviations over the period of 1995:05–2012:10 are estimated and consequently used to identify the main determinants of the industry cycle. It is found that the Philadelphia Semiconductor Index and total inventories in various downstream industries have important roles in signaling the industry growth. The results from an out-of-sample forecasting exercise also reveal the predictive potential and usefulness of BMA for the long-term prediction.

Femtosecond Single-Pulse Absorption in Semiconductors with varying Dopant Concentration

The influence of dopant concentration on the absorption of femtosecond mid-IR pulses is described. The measured results are compared to a theoretical absorption model. Summary Bulk material modification based on focused femtosecond irradiation has attracted wide interest for the fabrication of photonics devices such as waveguides [1], Fresnel optics [2], active on-chip devices [3] or micro-fluidic structures [4]. Besides its true 3D structuring capabilities[5], simple implementation of device changes and cost-reduction for small value production are some of this technology’s advantages. However, so far it has mainly been applied to dielectric host-materials, such as transparent glasses or crystals. Full integration towards silicon photonics has not been achieved. Extending 3D femtosecond laser direct write (FLDW) technology from such dielectric materials towards semiconductor materials could enable new applications for micro-electronic processing. Adoption of 3D FLDW technology for semiconductor processing requires a fundamental understanding of the differences of the irradiation requirements, and possible modification processes in this host material. In addition, due to the two- to three-fold increase in refractive index of semiconductors compared to dielectrics, challenges regarding focusing and aberrations have to be addressed and overcome. In this presentation we show results of our investigation of the modification threshold of crystalline silicon, and its dependence on wavelength and dopant concentration.. Differences in the absorption behavior of this new host material will be explained based on theoretical models. In addition we describe a new measurement technique to extract the material response in bulk semiconductors will be given.

The Rahman-Nat diffraction on a thin laser-induced grating of the refractive index in semiconductors

The Rahman-Nat diffraction on a thin laser-induced grating of the refractive index in semiconductors

Achieving superior band gap, refractive index and morphology in composite oxide thin film systems violating the Moss rule

The interrelation between energy gap and high frequency refractive index in semiconductors and dielectrics is manifested by an inverse law which is popularly known as the Moss rule. This semi-empirical relationship is based on the fundamental principle that in a dielectric medium all energy levels are scaled down by a factor of the square of the dielectric constant. Such a rule is obeyed by most pure semiconductors and dielectrics with a few rare violations in composite materials which display several interesting parametric and microstructural evolutions. The present results are based on some specific oxide composite thin films involving Gd2O3/SiO2 and ZrO2/SiO2 codeposited systems that have displayed a superior refractive index and energy gaps violating the semi-empirical Moss rule. Also, morphological supremacy is also distinctly noticed in these composites. The novel microstructural and polarizability properties of such composite systems were probed through multi-mode atomic force microscopy and phase modulated spectroscopic ellipsometry using refractive index modelling, autocorrelation and height–height correlation functional analyses. These binary composite thin films have shown their potential as well as the possibility of meeting expectations in satisfying the challenging optical coating requirements of the deep ultraviolet spectral region.

Moore's Law, Competition, and Intel's Productivity in the Mid-1990s

In the mid-1990s, a pickup in measured productivity growth for the semiconductor industry coincided with an economy-wide acceleration in labor productivity growth. The pickup in semiconductor markets reflected an increase in the growth of real output that was generated by what Dale Jorgenson (2001) called an “inflection point” in the price indexes for the semiconductor industry. Jorgenson hypothesized that the inflection point reflected increases in the rate of product innovation made possible by an increase in Moore’s Law, a stylized description of technology that currently states that the number of electrical components on a chip will double every eighteen months. Within semiconductors, microprocessors (MPUs) produced by Intel—the world’s largest producer of the chips that serve as a computer’s central processing unit—were the primary contributor to the inflection point in the semiconductor index. The inflection point in the price index coincided with two changes in the price contours for Intel’s chips. First, price contours for Intel’s chips became steeper around 1995. Because most price index formulae boil down to functions of weighted averages of price change, steeper price contours translate directly into more rapidly declining price indexes. At the same time, the product lifecycle for MPUs—the length of time chips are sold in the market—shortened and Intel began to introduce chips more frequently. What caused these changes in pricing and product cycles? This paper provides a simple framework to help gain some intuition on these issues. The model provides a set of conditions under which an increase in Moore’s Law is consistent with both of these stylized facts. In the model, an increase in Moore’s Law raises the quality of future chips relative to today’s chips. If consumers view these chips as substitutes, then increases in the quality of tomorrow’s chips push down the prices for today’s chips and can, under certain conditions, generate an inflection point in the price index. However, the framework also suggests that changes in the attributes of contemporaneous substitutes can have the same effects. Thus, the model suggests that increases in the quality of competitor’s chips can generate an inflection point through the same channel. This is an important possibility to consider because Intel faced increasing competition from AMD beginning in the mid-1990s, about when the inflection point occurred.

Features of coherent laser beams interaction with condensed matter

Some mechanisms of formation of laser-induced periodic surface and bulk structures in condensed matter are considered. Their influence on optical properties of semiconductors is investigated. It is shown that under action of coherent laser beams (CLBs) a grating of the refraction index arises in semiconductors. The models featuring this effect are offered. The relevant theoretical calculations confirming occurrence the new phenomenon — appearance of a grating of the refractive index in semiconductors in a field of CLBs — were carried out. It is shown that in ferromagnetic semiconductors (FMSC) with a laser-induced grating of the magnon temperature one probably deals with occurrence of the nonlinearity of the refraction index caused by the nonlinearity of FMSC magnetic susceptibility and one should observe oscillations of a refraction index, which will result in occurrence of complementary darkened areas.

Far-infrared transient-resonant Faraday rotation induced by non-equilibrium electrons in compensated p-InSb under pulsed-photoexcitation

We have made our first attempt to investigate the resonant-transient Faraday effect induced by conduction and bound electrons in compensated p-InSb under pulsed-photoexcitation at 4.2 K with use of a far-infrared laser. The Faraday rotation angle is extremely sensitive to the refractive index for the left-hand and right-hand circularly polarized waves. Meanwhile ionized donors in compensated semiconductors are neutralized by photoexcitation and the resonant phenomena by these neutralized impurities bring a big change of refractive index in semiconductors. As donor electrons excited by the photo-pulse relax with a finite lifetime, the refractive index dominated by these donor electrons has time-dependent nature, and thus we are able to observe the transient-Faraday effect through the time-resolved experiments.

Atomic radiation rates in photonic crystals

A photonic crystal, defined as a periodic dielectric structure, can influence the radiation rate of an embedded dipolar emitter. A theory of this effect is developed and the efficiency of a dipolar photonic source is calculated for a realistic three-dimensional crystal. Taking as a starting point the photonic band structure and its associated eigenfields, it is shown that the emission rate is strongly correlated with the density of modes, but also that the density of modes alone cannot explain all features found in the emission spectrum. For an infinite crystal, the computation of the field propagator confirms that the emission rate falls to zero in the frequency range defined by the photonic band gap. The emitter lifetime changes with the dipole location and orientation, leading to a radiation rate enhancement or inhibition according to the direction of the emission. These results may open routes to photonic sources with very high quantum efficiency. One of the early motivations for the study of photonic crystals ~PC’s ! has been their potential for the control of electromagnetic radiation from quantized sources. The pioneering work of Yablonovitch 1 suggested that optical bandgap materials could inhibit spontaneous emission. Thus, for instance, a spatial modulation of the refractive index in semiconductors could prevent the direct-gap electron-hole radiative recombination if the radiation frequency happened to lie in the range of the photonic gap. The control of the random spontaneous emission could also have important consequences on the reduction of noise in optoelectronic devices. Beyond the simple control of spontaneous emission, photonic crystals could provide paths to photon sources engineering. Being able to modify radiation rates in specific directions could have far-reaching consequences on the physics of light sources. It is currently thought, for instance, that obliterating the junction emission of a light-emitting diode in directions where total reflection on the packaging case would preclude photon escape, while enhancing the emission rate in more favorable directions, could lead to a dramatic improvement of the overall quantum efficiency of the device. Near-perfect light-generating systems which could follow may have as large an impact as Edison’s invention of incandescence light. Surprisingly, few experiments have been performed on molecular lifetime changes in PC. 2‐5 Preparation difficulties of a well-defined system, particularly the embedding of dye molecules inside the PC, conduct to different interpretations, subject to controversy. 6,7 However, these experiments have first been concerned with dye molecules embedded in Bravais fcc structures of dielectric spheres. It appears that the modification of the spontaneous emission is found to be weak due to the absence of a complete band gap with such structures. Recently, an inverse opal, that is an actual photonic band-gap material, has been used. It unambiguously shows the important expected changes. 5

Double-Doppler wavelength conversion of infrared optical pulses by moving grating of refractive index in semiconductors

A time-domain model of an excited semiconductor medium as a moving Bragg grating was used to investigate a double-Doppler wavelength conversion of an infrared (λ0 = 1.5 μm) 0.8 ps width optical pulse. In order to calculate ultrafast electromagnetic transients, a time-domain Volterra integro-differential equation was used for simulations. It is shown here that the high drift velocity of carriers in an InAs semiconductor produces a 3.5 nm up and down (9.7 THz) conversion span. The converted pulse width and spectral density strongly depend on the contrast of permittivity modulation. The depth of modulation has to be at least 5–7. A −3 dB conversion efficiency can be gained with a depth of modulation more than 7 and a length of semiconductor layer greater than 20 μm.

Empirical temperature dependence of the refractive index of semiconductors

Values of the temperature coefficient of the refractive index were obtained from the derivation of a simple relation between energy band-gap and refractive index in semiconductors. These values, (dn/dT)/n, were compared to the experimental data found in literature. Our model, with only one fitting parameter dB/dT=2.5×10−5 K−1 for all semiconductors, results in the best agreement with experimental data.

Temperature dependence of the refractive index in semiconductors

The temperature coefficients of the refractive indices of Ge, Si, InAs, GaAs, InP, GaP, CdSe, ZnSe, and ZnS are measured by a prism technique in spectral ranges of up to λ = 12 μm at 15–35°C. Numerical values of equivalent oscillator parameters describing the n(λ) dispersion, as well as the high-frequency ∊∞ and low-frequency ∊0 dielectric constants, are determined with precision. Taking into account the band structure of the above semiconductors, the values dn/dT have been calculated and show good agreement with experimental data.

The dispersion of the refractive index of semiconductors at the edge of their intrinsic absorption

The authors discuss the frequency dependence of the refractive index of various semiconductors near the edge of their intrinsic absorption in both theory and experiment. Beginning with random phase approximation, equations are presented which include all possible excitations and result in values for the width of the forbidden energy gap, the oscillator strengths, and spectral functions for the absorption coefficients. Data are presented for the following materials: CdS, CdSe, CdTe, GaSb, InP, GaAs, ZnTe, PbTe, InAs, InSb, and ZnSe.