Majority-Carrier Mobilities in Undoped and \textit{n}-type Doped ZnO Epitaxial Layers

Transparent and conductive ZnO:Ga thin films are prepared by laser molecular-beam epitaxy. Their electron properties were investigated by the temperature-dependent Hall-effect technique. The 300-K carrier concentration and mobility were about $n_s \sim 10^{16}$ cm$^{-3}$ and 440 cm$^{2}$/Vs, respectively. In the experimental `mobility vs concentration' curve, unusual phenomenon was observed, i.e., mobilities at $n_s \sim 5\times$ 10$^{18}$ cm$^{-3}$ are significantly smaller than those at higher densities above $\sim 10^{20}$ cm$^{-3}$. Several types of scattering centers including ionized donors and oxygen traps are considered to account for the observed dependence of the Hall mobility on carrier concentration. The scattering mechanism is explained in terms of inter-grain potential barriers and charged impurities. A comparison between theoretical results and experimental data is made.Comment: 5 pages, 1 figure, conference on II-VI compounds, RevTe

Various preconcentrator structures for determination of acetone in a wide range of concentration

In this paper, the investigation results on preconcentration of acetone at various initial concentrations are presented. The structures were made of conventional materials, such as stainless steel, quartz tube as well as fabricated in MEMS technology - micropreconcentrators. All structures have the same ‘active’ area to obtain more suitable comparison. The adsorbent materials were selected from commercial available Sigma-Aldrich Carbon Adsorbent Sampler Kit, consisting of 8 various adsorbents. The highest concentration factors were obtained by utilization of micropreconcentrator filled with Carboxen-1018, which is recommended for adsorption of C2-C3 compounds. The preconcentrators were placed into microsystem, and semiconductor gas sensor array was used as a detector unit. The microsystem was previously tested and designed for exhaled breath acetone analysis. The obtained results show that micropreconcentrator can be a useful tool for an increasing sensor sensitivity

AMORPHOUS HYDROGENATED SILICON FILMS STUDIED BY SCHOTTKY BARRIER METHOD

The problem of the effective ohmic junction and the question of the barrier height for thin film structures of Αl/a-Si:H/n+c-Si/Al and Al/a-Si:H/n+c--Si/Mo are studied. Current-voltage and temperature characteristics were measured and possible mechanisms of conductivity were extracted and discussed. This study is a part of series of experiments in which the problem of the effective ohmic junction and the question of the barrier height in the thin film stuctures are investigated. Various types of sandwich structures were prepared, as shown in the Schottky diodes were fabricated in a sandwich structure. Molybdenum or aluminum sputtered onto glass substrate, served as the back contact. An ohmic contact characterized by effective electron injection to a-Si:H, was only obtained if additional film of 0.3 μm polycrystalline silicon was sputtered in an 99% of argon and 1% of phosphin atmosphere. Then, the a-Si:H film and top Schottky electrode were deposited on the substrate. Active area of the junction was 0.005 cm 2 . Diode rectification ratios about 10 4 are observed at room temperature, as shown i

Growth of n-type γ-CuCl with improved carrier concentration by pulsed dc sputtering: structural, electronic and UV emission properties

Copper (I) chloride is naturally a direct band gap, zincblende and p-type semiconductor material with much potential in linear and non-linear optical applications owing to its large free excitonic binding energy. In order to fabricate an efficient electrically pumped emitter, a combination of both p-type and n-type semiconductor materials will be required. In this study, we report on the growth of n-type γ-CuCl with improved carrier concentration by pulsed dc magnetron sputtering of CuCl/Zn target. An improvement of carrier concentration up to an order of ~ 9.8x1018 cm-3, which is much higher than the previously reported (~ 1016 cm-3), has been achieved. An enhancement in crystallinity of CuCl along the (111) orientation and its consistency with the morphological studies have also been investigated as an effect of doping. Influence of Zn wt % in the sputtering target on the Hall mobility and resistivity of the doped films is explored. The strong ultraviolet emission of doped films is confirmed using room temperature and low temperature photoluminescence studies

Microsystem in LTCC technology for measurements of gas concentration in a sub-ppm range

Commonly used substrates for resistance-type oxide sensors are mainly alumina plates. Other types of ceramics, e.g. based on Low Temperature Cofired Ceramics (LTCC) technology could also be used for this purpose. This technology is well established and enables a creation of 3D structures with channels and cavities that can be formed inside a LTCC micromodule. The work describes manufacturing of the microsystem containing a gas preconcentration chamber and sensor substrates with improved thermal properties, all fabricated in LTCC technology

The future of 5G and beyond : leadership, deployment and European policies

Published online: 04 September 2023This paper discusses the need for a strategic rethinking of the policies that promote 5G development and deployment in Europe, as they are crucial in determining the future impact of 5G and later also 6G on the digital economy. Considering the current state of 5G deployment and insights that have emerged from the debate on 5G technological leadership, we discuss the need for a more effective and proactive policy from the European Union in this field. The main suggestion is to develop an industrial policy that contrasts fragmentation in the telecommunications sector by taking the whole European Union as the scale of action, instead of just the individual member states.This article was published Open Access with the support from the EUI Library through the CRUI - Elsevier Transformative Agreement (2023-2027)

Position statement on the European commission’s call for evidence for an impact assessment on standard-essential patents

On 14th February 2022, the European Commission published a ‘Call for evidence for an impact assessment’ (Call for Evidence) and Public Consultation related to a new framework for standard essential patents (SEPs). The Florence School of Regulation: Area Communications & Media (FSR C&M) of the European University Institute (EUI) is thankful for the opportunity to provide its feedback. Our team of researchers has significant research, policy and training experience in the areas of telecommunications regulation, standardisation and EU competition policy. In this paper, we focus on four specific points raised by the Call for Evidence: 1) the necessity and proportionalityof any SEP licensing policy measure; 2) the measures that increase the transparency of the SEP landscape; 3) the optimal level of licensing in the production chain; 4) the alternative dispute resolution mechanisms for Fair, Reasonable and Non-Discriminatory (FRAND) licenses. Our contribution aims to be a catalyst for the debate about the appropriate SEP licensing framework

Position statement on the Joint ITA–NIST–USPTO collaboration initiative regarding standards : notice of public listening and request for comments

On 11th September 2023, the US Patent and Trademark Office (USPTO), the International Trade Administration (ITA), and the National Institute for Standards and Technology (NIST) called for stakeholder input on the current state of U.S. firm participation in standard-setting, and the ability of U.S. industry to readily adopt standards to grow and compete, especially as they relate to the standardisation of critical and emerging technologies. The Centre for a Digital Society (CDS) of the European University Institute (EUI) is thankful for the opportunity to offer its comments. We would like to express our view on the legislative proposal of the European Commission (EC) for a Regulation on Standard Essential Patents (hereinafter, the Regulation) as it relates to question no. 1 of the Request for Comments on the impact of foreign IPR policies on US leadership and participation in international standard setting. Furthermore, concerning question no. 9 on possible standard-essential patents (SEP) transparency measures, we highlight the possibility of improving the USPTO patent register already in place

Position statement on the European Commission’s proposal for a SEPs regulation

On 27th April 2023, the European Commission published a proposal for a Regulation on Standard Essential Patents (hereinafter, SEPs Regulation) and allowed the public to provide feedback. The Centre for a Digital Society (CDS) of the European University Institute (EUI) is thankful for the opportunity to offer its comments and make suggestions on the proposed Regulation. Our team of researchers has significant research, policy and training experience in the areas of intellectual property, telecommunications regulation, standardisation and EU competition policy. In this Position Statement, we caution against adopting the proposed SEPs Regulation in its current form and suggest adopting guidance under Arts. 101 and 102 TFEU to clarify how SEP licensing should occur not to breach EU competition law. In the sub-optimal scenario where EU institutions would continue to pursue an immediate regulatory intervention, we provide substantial suggestions in an attempt to improve the current proposal of SEPs Regulation and limit certain negative consequences. Our constructive criticism aims to be a catalyst for the debate in the legislative process about the appropriate SEP licensing framework