Person: Martil De La Plaza, Ignacio
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First Name
Ignacio
Last Name
Martil De La Plaza
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Electrónica
Identifiers
130 results
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Now showing 1 - 10 of 130
Item Inversion charge study in TMO hole-selective contact based solar cells(IEEE Journal of Photovoltaics, 2023) García Hernansanz, Rodrigo; Pérez Zenteno, F.; Duarte Cano, S.; Caudevilla Gutiérrez, Daniel; Algaidy, S.; García Hemme, Eric; Olea Ariza, Javier; Pastor Pastor, David; Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; Ros, E.; Puigdollers, J.; Ortega, P.; Voz, C.In this article, we study the effect of the inversion charge ( Q _inv ) in a solar cell based on the hole-selective characteristic of substoichiometric molybdenum oxide (MoO_x ) and vanadium oxide (VO_x ) deposited directly on n-type silicon. We measure the capacitance–voltage ( C – V ) curves of the solar cells at different frequencies and explain the results taking into account the variation of the space charge and the existence of Q_inv in the c-Si inverted region. The high-frequency capacitance measurements follow the Schottky metal–semiconductor theory, pointing to a low inversion charge influence in these measurements. However, for frequencies lower than 20 kHz, an increase in the capacitance is observed, which we relate to the contribution of the inversion charge. In addition, applying the metal–semiconductor theory to the high-frequency measurements, we have obtained the built-in voltage potential and show new evidence about the nature of the conduction process in this structure. This article provides a better understanding of the transition metal oxide/n-type crystalline silicon heterocontact.Item Electronic transport properties of Ti-supersaturated Si processed by rapid thermal annealing or pulsed-laser melting(Semiconductor Science and Technology, 2022) Olea Ariza, Javier; González Díaz, Germán; Pastor Pastor, David; García Hemme, Eric; Caudevilla Gutiérrez, Daniel; Algaidy, S; Pérez-Zenteno, F.; Duarte-Cano, S.; García Hernansanz, Rodrigo; Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, IgnacioIn the scope of supersaturated semiconductors for infrared detectors, we implanted Si samples with Ti at high doses and processed them by rapid thermal annealing (RTA) to recover the crystal quality. Also, for comparative purposes, some samples were processed by pulsed-laser melting. We measured the electronic transport properties at variable temperatures and analyzed the results. The results indicate that, for RTA samples, surface layers with a high Ti concentration have negligible conductivity due to defects. In contrast, the implantation tail region has measurable conductivity due to very high electron mobility. This region shows the activation of a very shallow donor and a deep donor level. While deep levels have been previously reported for Ti in Si, such a shallow level has never been measured, and we suggest that it originates from Ti-Si complexes. Finally, a decoupling effect between the implanted layer and the substrate seems to be present, and a bilayer model is applied to fit the measured properties. The fitted parameters follow the Meyer–Neldel rule. The role of the implantation tails in Si supersaturated with Ti is revealed in this work.Item Ti supersaturated Si by microwave annealing processes(Semiconductor Science and Technology, 2023) Olea Ariza, Javier; González Díaz, Germán; Pastor Pastor, David; García Hemme, Eric; Caudevilla Gutiérrez, Daniel; Algaidy, S.; Perez Zenteno, F.; Duarte Cano, S.; García Hernansanz, Rodrigo; Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; Lee, Yao-Jen; Hong, Tzu-Chieh; Chao, Tien-ShengMicrowave annealing (MWA) processes were used for the first time to obtain Ti supersaturated Si. High Ti doses were ion implanted on Si substrates and subsequently MWA processed to recrystallize the amorphous layer. The resulting layers were monocrystalline with a high density of defects. Ti depth profiles indicate that diffusion is avoided once recrystallization is produced. Finally, the electronic transport properties measurements point to a decoupling effect between the Si:Ti layer and the substrate. The implanted layer present also a shallow donor and very high Hall mobility.Item Growth and characterization of CuxAg1-xInSe2 thin films by pulsed laser deposition(Solid State Phenomena, 1999) Gremenok, Valery; Bodnar, Ivan; Martil De La Plaza, Ignacio; Martines, F.L.; Sergeev-Nekrasov, Sergei; Victorov, I.A.We report on structural and optical measurements made on thin films of the quaternary compounds CuxAg1-xInSe2(x = 0; 0.3; 0.5; 0.7; 1.0). The films were prepared by pulsed laser deposition (PLD) of prereacted material onto glass substrates. The substrate temperature was about 450-480 degrees C. The beam of a Nd:YAG laser was directed onto a rotating target. The resulting films were characterized by XRD, SEM, and EDAX, The films were single phase, polycrystalline and stoichiometric within 4 %. The refractive index n and the absorption coefficient alpha of CuxAg1-xInSe2 thin films were obtained by measuring the transmittance (T) and reflectance (R) in the photon energy range from 0.4 to 2.5 mu m. The optical properties were determined from rigorous expression for the transmission and reflection in an air/film/glass substrate/air multilayer system. The films had high optical absorption about 10(4) - 10(5) cm(-1) and the band gaps of 0.99 eV (CuInSe2) and 1.25 eV (AgInSe2). The energy gaps observed in laser-deposited CuxAg1-xInSe2 thin films near and above the fundamental absorption edge exhibit a nonlinear composition dependence.Item Thermal stability of a-SiNx: H films deposited by plasma electron cyclotron resonance(Journal of vacuum science & technology a: Vacuum surfaces and films, 1999) González Díaz, Germán; Martil De La Plaza, Ignacio; Prado Millán, Álvaro DelWe analyze the influence of rapid thermal annealing on Al/SiNx:H/Si structures with a nitrogen to silicon ratio of 1.55 in the insulator bulk. The SiNx:H is deposited by the electron cyclotron resonance plasma method and the films were annealed at temperatures ranging from 300 to 1050 degrees C. We have related the changes of the interface trap density with those of the insulator bulk density of dangling bonds, resistivity, and breakdown field. A sharp dip in the dangling bond density is observed at moderate annealing temperatures, from 1.8 X 10(18) cm(-3) for the as-deposited film down to 9.6 X 10(16) cm(-3) at the point of inversion of the trend between 500 and 600 degrees C. The density of interface states is also reduced in this range of temperatures from 3.6 X 10(11) to 1.2 X 10(11) eV(-1) cm(-2). Resistivity and breakdown held are maintained in the range 5 X 10(14)-5 X 10(15) Ohm cm and 6.4-6.6 MV/cm, respectively, up to a temperature of 600 degrees C. We attribute the improvement of the interface characteristics and the decrease of dangling bonds to a thermal relaxation and reconstruction of the SiNx:H lattice and its interface with the silicon substrate. For temperatures above this threshold the electrical properties suddenly deteriorate and the density of dangling bonds increase. At even higher temperatures (above 900 degrees C) a release of hydrogen from N-H bonds takes place. (C) 1999 American Vacuum Society. [S0734-2101(99)05304-X].Item A robust method to determine the contact resistance using the van der Pauw set up(Measurement, 2017) González Díaz, Germán; Pastor, D.; García Hemme, Eric; Montero, Daniel; García Hernansanz, Rodrigo; Olea Ariza, Javier; Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, IgnacioThe van der Pauw method to calculate the sheet resistance and the mobility of a semiconductor is a pervasive technique both in the microelectronics industry and in the condensed matter science field. There are hundreds of papers dealing with the influence of the contact size, nonuniformities and other second order effects. In this paper we will develop a simple methodology to evaluate the error produced by finite size contacts, detect the presence of contact resistance, calculate it for each contact, and determine the linear or rectifying behavior of the contact. We will also calculate the errors produced by the use of voltmeters with finite input resistance in relation with the sample sheet resistance.Item Annealing effects on the interface and insulator properties of plasma-deposited Al/SiOxNyHz/Si devices(Semiconductor Science and Technology, 2004) Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; González Díaz, Germán; Kliefoth, K.; Füssel, W.We have studied and compared the effects of conventional annealing in a forming gas atmosphere (430 degreesC, 20 min) and rapid thermal annealing (RTA) in an inert Ar atmosphere (400-1000 degreesC, 30 s) on Al/SiOxNyHz/Si devices. The samples were deposited by the electron cyclotron resonance plasma method at low temperature (T = 200 degreesC). The devices were characterized by surface photovoltage measurements before applying contacts and by capacitance-voltage measurements. All the as-deposited samples containing N had positive flat-band voltage, which corresponds to negative charge in the insulator and/or in the interface states (Q(INS)). Additionally, trapping of positive charge is observed when measuring from inversion to accumulation after measuring from accumulation to inversion. This behaviour is tentatively attributed to the presence of defects related to N, such as the K centre (N-3=Siup arrow) or the N dangling bond (Si-2=Nup arrow), which may be present in a negatively charged state. For samples of SiO2 composition, with a negligible N content, Q(INS) is positive. High densities of interface states (D-it), above 10(12) eV(-1) cm(-2), are observed in the as-deposited samples. Both the annealing in a forming gas atmosphere and the RTA result in the change of the sign of Q(INS) from negative to positive and a decrease of its absolute value, as well as a decrease of D-it of about one order of magnitude. The trapping of positive charge is also greatly reduced. These improvements of the electrical properties are attributed to the passivation of defects by H present in the forming gas atmosphere or in the SiOxNyHz film itself in a non-bonded state. For RTA temperatures above 700 degreesC the properties of the devices degrade due to the release of H. The combination of RTA and annealing in a forming gas atmosphere results in the best properties.Item A comparative study of the electrical properties of TiO2 films grown by high-pressure reactive sputtering and atomic layer deposition(Semiconductor Science and Technology, 2005) Martil De La Plaza, Ignacio; González Díaz, Germán; San Andrés Serrano, EnriqueOxide-semiconductor interface quality of high-pressure reactive sputtered (HPRS) TiO2 films annealed in O-2 at temperatures ranging from 600 to 900 degrees C, and atomic layer deposited (ALD) TiO2 films grown at 225 or 275 degrees C from TiCl4 or Ti(OC2H5)(4), and annealed at 750 degrees C in O-2, has been studied on silicon substrates. Our attention has been focused on the interfacial state and disordered-induced gap state densities. From our results, HPRS films annealed at 900 degrees C in oxygen atmosphere exhibit the best characteristics, with D-it density being the lowest value measured in this work (5-6 x 10(11) cm(-2) eV(-1)), and undetectable conductance transients within our experimental limits. This result can be due to two contributions: the increase of the SiO2 film thickness and the crystallinity, since in the films annealed at 900 degrees C rutile is the dominant crystalline phase, as revealed by transmission electron microscopy and infrared spectroscopy. In the case of annealing in the range of 600-800 degrees C, anatase and rutile phases coexist. Disorder-induced gap state (DIGS) density is greater for 700 degrees C annealed HPRS films than for 750 degrees C annealed ALD TiO2 films, whereas 800 degrees C annealing offers DIGS density values similar to ALD cases. For ALD films, the studies clearly reveal the dependence of trap densities on the chemical route used.Item A comparative study of anodic tantalum pentoxide and high-pressure sputtered titanium oxide(Journal of Materials Science: Materials in Electronics, 2003) Martil De La Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro Del; San Andrés Serrano, EnriqueIn this work we present a new method to fabricate improved TiO2 films by using a high-pressure sputtering system. In order to minimize the damage induced in the substrate surface by the ion bombardment, a high chamber pressure of 100 Pa is used, which is very much higher than typical values in conventional systems. We present results obtained by Xray diffraction and FTIR spectroscopy. Moreover, we will compare the properties of the resulting TiO2-insulator-metal capacitors with those of anodic Ta2O5. Very thin films of TiO2 have been obtained with a very promising quality for future electron device fabrication.Item Apuntes de Electrónica Analógica(2015) Franco Peláez, Francisco Javier; González Díaz, Germán; Martil De La Plaza, IgnacioApuntes de trabajo y exámenes resueltos de la Asignatura Electrónica Analógica, de la desaparecida Ingeniería Superior Electrónica. Asimismo, descripción de los modelos SPICE de los dispositivos electrónicos básicos.