The Impact of Carbon on Electronic Structure of N-Doped ZnO Films: Scanning Photoelectron Microscopy Study and DFT Calculations.

A Scanning Photoelectron Microscopy (SPEM) experiment has been applied to ZnO:N films deposited by Atomic Layer Deposition (ALD) under O-rich conditions and post-growth annealed in oxygen at 800 °C. spatial resolution (130 nm) allows for probing the electronic structure of single column of growth. The samples were cleaved under ultra-high vacuum (UHV) conditions to open atomically clean cross-sectional areas for SPEM experiment.

Anisotropy of radiation-induced defects in Yb-implanted β-GaO.

RE-doped β-GaO seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-GaO, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-GaO, namely the (-201) and (010).

Crystal Lattice Recovery and Optical Activation of Yb Implanted into β-GaO.

β-GaO is an ultra-wide bandgap semiconductor (E~4.8 eV) of interest for many applications, including optoelectronics. Undoped GaO emits light in the UV range that can be tuned to the visible region of the spectrum by rare earth dopants.

P-Type ZnO Films Made by Atomic Layer Deposition and Ion Implantation.

Zinc oxide (ZnO) is a wide bandgap semiconductor that holds significant potential for various applications. However, most of the native point defects in ZnO like Zn interstitials typically cause an n-type conductivity. Consequently, achieving p-type doping in ZnO is challenging but crucial for comprehensive applications in the field of optoelectronics.

Effect of Strain and Surface Proximity on the Acceptor Grouping in ZnO.

According to the present knowledge, the level of zinc oxide conductivity is determined by donor and acceptor complexes involving native defects and hydrogen. In turn, recently published low-temperature cathodoluminescence images and scanning photoelectron microscopy results on ZnO and ZnO/N films indicate grouping of acceptor and donor complexes in different crystallites, but the origin of this phenomenon remains unclear. The density functional theory calculations on undoped ZnO presented here show that strain and surface proximity noticeably influence the formation energy of acceptor complexes, and therefore, these complexes can be more easily formed in crystallites providing appropriate strain.

Atomic Layer Deposition of HfO Films Using TDMAH and Water or Ammonia Water.

Atomic layer deposition of HfO from TDMAH and water or ammonia water at different temperatures below 400 °C is studied. Growth per cycle (GPC) has been recorded in the range of 1.2-1.

Enhanced Luminescence of Yb Ions Implanted to ZnO through the Selection of Optimal Implantation and Annealing Conditions.

Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new fields of application due to the low-cost production. Ion implantation is a very promising technique to incorporate rare-earth dopants into ZnO.

Electrical and Structural Properties of Semi-Polar-ZnO/-AlO and Polar-ZnO/-AlO Films: A Comparative Study.

In this work, the properties of ZnO films of 100 nm thickness, grown using atomic layer deposition (ALD) on -(100) and -(001) oriented AlO substrate are reported. The films were grown in the same growth conditions and parameters at six different growth temperatures (T) ranging from 100 °C to 300 °C. All as-grown and annealed films were found to be polycrystalline, highly (001) oriented for the -AlO and highly (101) oriented for the -AlO substrate.

Charge Storage and Reliability Characteristics of Nonvolatile Memory Capacitors with HfO/AlO-Based Charge Trapping Layers.

Flash memories are the preferred choice for data storage in portable gadgets. The charge trapping nonvolatile flash memories are the main contender to replace standard floating gate technology. In this work, we investigate metal/blocking oxide/high-k charge trapping layer/tunnel oxide/Si (MOHOS) structures from the viewpoint of their application as memory cells in charge trapping flash memories.

Structural Properties of Thin ZnO Films Deposited by ALD under O-Rich and Zn-Rich Growth Conditions and Their Relationship with Electrical Parameters.

The structural, optical, and electrical properties of ZnO are intimately intertwined. In the present work, the structural and transport properties of 100 nm thick polycrystalline ZnO films obtained by atomic layer deposition (ALD) at a growth temperature (T) of 100-300 °C were investigated. The electrical properties of the films showed a dependence on the substrate (-AlO or Si (100)) and a high sensitivity to T, related to the deviation of the film stoichiometry as demonstrated by the RT-Hall effect.

Radiation Tolerance and Charge Trapping Enhancement of ALD HfO/AlO Nanolaminated Dielectrics.

High- dielectric stacks are regarded as a promising information storage media in the Charge Trapping Non-Volatile Memories, which are the most viable alternative to the standard floating gate memory technology. The implementation of high-k materials in real devices requires (among the other investigations) estimation of their radiation hardness. Here we report the effect of gamma radiation (Co source, doses of 10 and 10 kGy) on dielectric properties, memory windows, leakage currents and retention characteristics of nanolaminated HfO/AlO stacks obtained by atomic layer deposition and its relationship with post-deposition annealing in oxygen and nitrogen ambient.

Highly efficient SERS-based detection of cerebrospinal fluid neopterin as a diagnostic marker of bacterial infection.

A highly efficient recognition unit based on surface-enhanced Raman spectroscopy (SERS) was developed as a promising, fast, and sensitive tool for detection of meningococcal meningitis, which is an extremely serious and often fatal disease of the nervous system (an inflammation of the lining around the brain and spinal cord). The results of this study confirmed that there were specific differences in SERS spectra between cerebrospinal fluid (CSF) samples infected by Neisseria meningitidis and the normal CSF, suggesting a potential role for neopterin in meningococcal meningitis detection and screening applications. To estimate the best performance of neopterin as a marker of bacterial infection, principal component analysis (PCA) was performed in a selected region (640-720 cm(-1)) where the most prominent SERS peak at 695 cm(-1) arising from neopterin was observed.

ZnO oxide films for ultrasensitive, rapid, and label-free detection of neopterin by surface-enhanced Raman spectroscopy.

Efficient and low-cost surface-enhanced Raman scattering (SERS) substrates based on Au coated zinc oxide layers for the detection of neopterin were prepared. These substrates showed high sensitivity to p-mercaptobenzoic acid (p-MBA) at a low concentration of 10(-9) M and an enhancement factor of over 10(7) was achieved. The uniform density of SERS-active "hot-spots" on a Si/ZnO/Au surface results in high reproducibility towards detecting p-MBA at 50 different, randomly selected positions on a single substrate (RSD = 9%) and on six different SERS substrates prepared under identical conditions (RSD = 11%).