Markus Bosund

Ytterbium-doped fibers fabricated with atomic layer deposition method

We report on a new fabrication method of producing ytterbium doped fibers by atomic layer deposition (ALD) in combination with the conventional modified chemical vapor deposition (MCVD) technique. An MCVD soot-preform with a porous layer of SiO(2) is coated with layers of Yb(2)O(3) and Al(2)O(3) prior to sintering, using the gas-phase ALD method. An SEM/EDS material analysis study shows that the dopants successfully penetrate the full thickness of 320 µm of the soot layer. An Yb-doped fiber fabricated by this technique shows a background attenuation of 20 dB/km, a uniform longitudinal Yb-doping profile, and good laser characteristics with a slope efficiency of 80%. Furthermore, we present a comparison in terms of photodarkening between the MCVD-ALD fiber and a solution doped fiber, fabricated with the same MCVD recipe. The new MCVD-ALD fiber appears to be more photodarkening resistant.

High-k GaAs metal insulator semiconductor capacitors passivated by ex-situ plasma-enhanced atomic layer deposited AlN for Fermi-level unpinning

This paper examines the utilization of plasma-enhanced atomic layer deposition grown AlN in the fabrication of a high-k insulator layer on GaAs. It is shown that high-k GaAs MIS capacitors with an unpinned Fermi level can be fabricated utilizing a thin ex-situ deposited AlN passivation layer. The illumination and temperature induced changes in the inversion side capacitance, and the maximum band bending of 1.2 eV indicates that the MIS capacitor reaches inversion. Removal of surface oxide is not required in contrast to many common ex-situ approaches.

Comparison of ammonia plasma and AlN passivation by plasma-enhanced atomic layer deposition

Surface passivation of GaAs by ammonia plasma and AlN fabricated by plasma-enhanced atomic layer deposition are compared. It is shown that the deposition temperature can be reduced to 150 °C and effective passivation is still achieved. Samples passivated by AlN fabricated at 150 °C show four times higher photoluminescence intensity and longer time-resolved photoluminescence lifetime than ammonia plasma passivated samples. The passivation effect is shown to last for months. The dependence of charge carrier lifetime and integrated photoluminescence intensity on AlN layer thickness is studied using an exponential model to describe the tunneling probability from the near-surface quantum well to the GaAs surface.

Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SFx+ and O+ chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF6 based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SFx+ and O+ chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF6 based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.

ATOMIC LAYER DEPOSITION HfO2 FILM USED AS BUFFER LAYER OF THE Pt/(Bi0.95Nd0.05)(Fe0.95Mn0.05)O3/HfO2/Si CAPACITORS FOR FeFET APPLICATION

Neodymium and manganese-doped BiFeO3 — (Bi0.95Nd0.05)(Fe0.95Mn0.05)O3(BNFMO) ferroelectric film and HfO2 layer with different thickness were fabricated using metal-organic decomposition and atomic layer deposition (ALD) method, respectively. Metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with 200 nm thick BNFMO and 5 nm thick HfO2 layer on silicon substrate have been prepared and characterized. It is found that there is no distinct interdiffusion and reaction occurring at the interface between BNFMO/HfO2 and HfO2/Si. The capacitance–voltage (C–V) and leakage current properties of Pt/HfO2/Si capacitors with different HfO2 thickness were studied. The MFIS structure showed clockwise C–V hysteresis loops due to the ferroelectric polarization of BNFMO. The maximum memory window is 5 V. The leakage current of the Pt/BNFMO/HfO2/Si capacitor was about 2.1 × 10-6 A/cm2 at an applied voltage of 4 V.

Tribological properties of thin films made by atomic layer deposition sliding against silicon

Interfacial phenomena, such as adhesion, friction, and wear, can dominate the performance and reliability of microelectromechanical (MEMS) devices. Here, thin films made by atomic layer deposition (ALD) were tested for their tribological properties. Tribological tests were carried out with silicon counterpart sliding against ALD thin films in order to simulate the contacts occurring in the MEMS devices. The counterpart was sliding in a linear reciprocating motion against the ALD films with the total sliding distances of 5 and 20 m. Al2O3 and TiO2 coatings with different deposition temperatures were investigated in addition to Al2O3-TiO2-nanolaminate, TiN, NbN, TiAlCN, a-C:H [diamondlike carbon (DLC)] coatings, and uncoated Si. The formation of the tribolayer in the contact area was the dominating phenomenon for friction and wear performance. Hardness, elastic modulus, and crystallinity of the materials were also investigated. The nitride coatings had the most favorable friction and wear performance of the...

Rotary Spatial Plasma Enhanced Atomic Layer Deposition — An enabling manufacturing technology for µm-thick ALD films

Atomic Layer Deposition (ALD) is well known for its high film quality and high conformality, but limited by the low deposition rate. Beneq proposes a novel approach using Rotary Spatial Plasma Enhanced ALD process, which can reach deposition rates 10× higher than traditional pulsed ALD. This technology also enables use of PEALD in batch mode with high throughput. This paper describes the technology in more details.

A novel all-vapor phase fabrication process for ytterbium-doped fibers with atomic layer deposition method

We present a novel all-vapor phase fabrication method for producing Yb-doped fibers by atomic layer deposition (ALD) in combination with the well-established modified chemical vapor deposition (MCVD) technique.

Atomic layer deposition for fabrication of ytterbium doped fibers

Atomic layer deposition (ALD) was used to fabricate an ytterbium (Yb)-doped silica fiber in combination with the conventional modified chemical vapor deposition (MCVD) method. An MCVD soot-preform with a porous layer of SiO2 doped with GeO2 was coated with layers of Yb2O3 and Al2O3 prior to sintering, using the ALD method. ALD is a surface controlled CVD-type process enabling thin film deposition over large substrates with good thickness control, uniformity and high conformality. A materials analysis study showed that the dopants successfully penetrated the full thickness of 320 μm of the soot layer. Preliminary preform and fiber experiments on refractive index profiles, background losses, lifetime and the characteristic gain-loss curve were performed demonstrating the potential of this method for fabricating Yb-doped fibers with high concentration of dopants.

Nd-doped Bismuth Titanate based ferroelectric field effect transistor: Design, fabrication, and optimization

Ferroelectric field effect transistor (FeFET) is a promising candidate in nonvolatile memory application due to its fast read/write speed, nondestructive readout, and low power consumption. Since the poor retention characteristic can be improved by introducing insulator buffer layers between gate layer and FET channel region, more and more attentions are devoted to the realization and optimization of this novel memory device [1]. Traditional ferroelectric materials, such as PZT [2, 3] and SBT [4] based FeFETs are extensively studied and reported in the past decades. Recently, Nd-doped Bismuth Titanate B3.15Nd0.85Ti3O12 (BNdT) with a large remnant polarization (2Pr=103µC/cm2) and outstanding fatigue endurance was reported by Chon et al. [5], and many ferroelectric applications are being processed based on this brand new ferroelectric material [6, 7]. In this letter, we fabricated a BNdT based FeFET for the first time. The fundamental structural and electrical properties are investigated correspondingly.