Person: San Andrés Serrano, Enrique
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First Name
Enrique
Last Name
San Andrés Serrano
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Electrónica
Identifiers
21 results
Search Results
Now showing 1 - 10 of 21
Item On the Optoelectronic Mechanisms Ruling Ti-hyperdoped Si Photodiodes(Advanced electronic materials, 2022) García Hemme, Eric; Caudevilla Gutiérrez, Daniel; Algaidy, Sari; Pérez Zenteno, Francisco José; García Hernansanz, Rodrigo; Olea Ariza, Javier; Pastor Pastor, David; Prado Millán, Álvaro Del; San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; González Díaz, Germán; García Hemme, EricThis work deepens the understanding of the optoelectronic mechanisms ruling hyperdoped-based photodevices and shows the potential of Ti hyperdoped-Si as a fully complementary metal-oxide semiconductor compatible material for room-temperature infrared photodetection technologies. By the combination of ion implantation and laser-based methods, approximate to 20 nm thin hyperdoped single-crystal Si layers with a Ti concentration as high as 10(20) cm(-3) are obtained. The Ti hyperdoped Si/p-Si photodiode shows a room temperature rectification factor at +/- 1 V of 509. Analysis of the temperature-dependent current-voltage characteristics shows that the transport is dominated by two mechanisms: a tunnel mechanism at low bias and a recombination process in the space charge region at high bias. A room-temperature sub-bandgap external quantum efficiency (EQE) extending to 2.5 mu m wavelength is obtained. Temperature-dependent spectral photoresponse behavior reveals an increase of the EQE as the temperature decreases, showing a low-energy photoresponse edge at 0.45 eV and a high-energy photoresponse edge at 0.67 eV. Temperature behavior of the open-circuit voltage correlates with the high-energy photoresponse edge. A model is proposed to relate the optoelectronic mechanisms to sub-bandgap optical transitions involving an impurity band. This model is supported by numerical semiconductor device simulations using the SCAPS software.Item Deposition of Intrinsic a-Si:H by ECR-CVD to Passivate the Crystalline Silicon Heterointerface in HIT Solar Cells(IEEE journal of photovoltaics, 2016) García Hernansanz, Rodrigo; García Hemme, Eric; Montero Álvarez, Daniel; Prado Millán, Álvaro Del; Olea Ariza, Javier; San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; González Díaz, GermánWe have deposited intrinsic amorphous silicon (a-Si:H) using the electron cyclotron resonance (ECR) chemical vapor deposition technique in order to analyze the a-Si:H/c-Si heterointerface and assess the possible application in heterojunction with intrinsic thin layer (HIT) solar cells. Physical characterization of the deposited films shows that the hydrogen content is in the 15-30% range, depending on deposition temperature. The optical bandgap value is always comprised within the range 1.9- 2.2 eV. Minority carrier lifetime measurements performed on the heterostructures reach high values up to 1.3 ms, indicating a well-passivated a-Si:H/c-Si heterointerface for deposition temperatures as low as 100°C. In addition, we prove that the metal-oxide- semiconductor conductance method to obtain interface trap distribution can be applied to the a-Si:H/c-Si heterointerface, since the intrinsic a-Si:H layer behaves as an insulator at low or negative bias. Values for the minimum of D_it as low as 8 × 10^10 cm^2 · eV^-1 were obtained for our samples, pointing to good surface passivation properties of ECR-deposited a-Si:H for HIT solar cell applications.Item High-quality single-crystalline epitaxial regrowth on pulsed laser melting of Ti implanted GaAs(Materials Science in Semiconductor Processing, 2023) Algaidy, Sari; Caudevilla Gutiérrez, David; Perez Zenteno, F.; García Hernansanz, Rodrigo; García Hemme, Eric; Olea Ariza, Javier; San Andrés Serrano, Enrique; Duarte Cano, S.; Siegel, J.; Gonzalo, J.; Pastor Pastor, David; Prado Millán, Álvaro DelWe present a detailed investigation on the formation of supersaturated GaAs using Ti+ implantation followed by nanosecond Pulsed Laser Melting (PLM). We have synthesized high-crystal quality supersaturated GaAs layers with concentrations of Ti above the insulator to metal transition (Mott limit). The Ti-implanted concentration depth profiles after PLM obtained by Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) show a redistribution of Ti impurities within the first hundred nanometers and superficial concentration up to 1 × 1021 redistrcm-3. Raman spectroscopy of these Ti supersaturated, and regrown GaAs samples shows a sharp crystalline peak and tensile strain due to the Ti lattice incorporation. Scanning Transmission Electron Microscopy (STEM) and high-resolution Transmission Electron Microscopy (TEM) images show a good GaAs crystallinity after the PLM process. Energy-Dispersive X-ray Spectroscopy (EDS) reveals an enhanced Ti signal inside bubble-like structures and an appearance of interface oxide layer with all processed samples.Item Limitations of high pressure sputtering for amorphous silicon deposition(Materials research express, 2016) García Hernansanz, Rodrigo; García Hemme, Eric; Montero Álvarez, Daniel; Olea Ariza, Javier; San Andrés Serrano, Enrique; Prado Millán, Álvaro Del; Ferrer, F. J.; Martil De La Plaza, Ignacio; González Díaz, GermánAmorphous silicon thin films were deposited using the high pressure sputtering (HPS) technique to study the influence of deposition parameters on film composition, presence of impurities, atomic bonding characteristics and optical properties. An optical emission spectroscopy (OES) system has been used to identify the different species present in the plasma in order to obtain appropriate conditions to deposit high purity films. Composition measurements in agreement with the OES information showed impurities which critically depend on the deposition rate and on the gas pressure. We prove that films deposited at the highest RF power and 3.4 × 10^−2 mbar, exhibit properties as good as the ones of the films deposited by other more standard techniques.Item High quality Ti-implanted Si layers above the Mott limit(Journal of Applied Physics, 2010) Martil De La Plaza, Ignacio; González Díaz, Germán; Olea Ariza, Javier; San Andrés Serrano, EnriqueIn this paper, we present a detailed characterization of high quality layers of Si implanted with Ti at high doses. These layers are intended to the formation of an intermediate band (IB) solar cell. The main requirement to obtain an IB material is to reach an impurity concentration beyond the Mott limit, which is, in this case, much higher than the solid solubility limit. To overcome this limit we used the combination of ion implantation and pulsed-laser melting as nonequilibrium techniques. Time-of-flight secondary ion mass spectrometry measurements confirm that Ti concentration exceeds the theoretical Mott limit in the implanted layer, and glancing incidence x-ray diffraction and transmission electron microscopy measurements prove that good crystallinity can be achieved. Sheet resistance and Hall effect mobility show uncommon characteristics that can only been explained assuming the IB existence.- Project number: 283
Item Integración de la formación teórica y experimental en el área de la Electrónica mediante el desarrollo de una plataforma de demostración del comportamiento real de los circuitos desarrollados en la docencia teórica(2020) San Andrés Serrano, Enrique; González Díaz, Germán; Prado Millán, Álvaro Del; Olea Ariza, Javier; Caudevilla Gutiérrez, Daniel; Herrera Fernández, Fernando; Paz López, Antonio 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.- Project number: 69
Item Mejora de las Metodologías Docentes para el área de la Electrónica(2018) San Andrés Serrano, Enrique; Martil De La Plaza, Ignacio; González Díaz, Germán; Prado Millán, Álvaro Del; García Hemme, Eric; Pastor Pastor, David; Olea Ariza, Javier; Lucía Mulas, María Luisa; Franco Peláez, Francisco Javier; Sánchez Balmaseda, Margarita María 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 High Pressure Sputtering of materials for selective contacts in emerging photovoltaic cells(2021 13th Spanish Conference on Electron Devices (CDE), 2021) San Andrés Serrano, Enrique; García Hernansanz, Rodrigo; Patricia Moreno, Gloria; García Hemme, Eric; Barrio, Rocío; Torres Almarza, Ignacio; Caudevilla Gutiérrez, Daniel; Pastor Pastor, David; Olea Ariza, Javier; Prado Millán, Álvaro Del; Algaidy, Sari; Zenteno Pérez, FranciscoIn this work we have explored the growth by high pressure sputtering (HPS) of materials intended for novel selective contacts for photovoltaic cells. This technique shows promise for the low-damage low-temperature deposition of PV materials. We studied the deposition of ITO, MoOx and TiOx using pure Ar and mixed Ar/O2 atmospheres as well as ceramic or metallic targets. We show that HPS deposition of these materials is feasible. The growth rate is greatly reduced when oxygen is added to the argon sputtering atmosphere. The best sputtering RF power was 20-45 W for the pressure range studied. Finally, as-deposited films present high surface recombination, but a mild hot plate anneal at 200ºC recovers long effective lifetimes.
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