| 1. |
- Almazidou, Maria, et al.
(författare)
-
Maria-mottagningarna i Stockholm, Göteborg och Malmö - Ungdomar i öppenvård år 2013
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trestad2 är en nationell satsning där de tre städerna Stockholm, Göteborg och Malmö samarbetar för att minska användandet av cannabis bland ungdomar. Inom ramen för projektet har det skapats en modell för att identifiera och följa trender i de tre storstäderna vad gäller droganvändning och psykosocial situation för ungdomar som påbörjar behandling för missbruksproblem. Framtagandet av relevanta indikatorer har skett i nära samarbete mellan praktiker och forskare utifrån en sammanvägning av forskningsmässiga, metodologiska och kliniskt betydelsefulla utgångspunkter. Underlaget utgörs av uppgifter om 788 ungdomar som inledde öppenvårdsbehandling vid någon av städernas Maria-mottagningar under år 2013 och har inhämtats med intervjumetoden UngDOK.Sammanställningen av indikatorer visar att flickor utgör cirka en fjärdedel av det totala antalet ungdomar som påbörjar öppenvård för problem med alkohol eller narkotika. Ungdomarnas medianålder när vårdkontakten inleds är 17 år och mer än hälften av ungdomarna har kommit i kontakt med Maria-mottagningarna via eget eller nätverkets initiativ. Nästan två tredjedelar av ungdomarna uppger att de har eller har haft omfattande problem under sin skolgång och cirka en tiondel av ungdomarna varken studerar, arbetar eller praktiserar. Drygt tre fjärdedelar av ungdomarna anger cannabis som sin primära drog, men nästan hälften av dem har även en riskfylld alkoholkonsumtion. Den genomsnittliga debutåldern för den primära drogen är 15 år. Ungefär en fjärdedel av ungdomarna har tidigare fått vård och behandling för alkohol- eller narkotikaproblem. Förekomsten av besvärliga uppväxtvillkor är hög hos ungdomarna och över hälften av dem har erfarenheter av att ha växt upp med våld, psykiska problem och/eller missbruk i familjen. Drygt en tredjedel av samtliga ungdomar har eller har haft kontakt med den psykiatriska vården.Vissa skillnader mellan de tre städernas Maria-mottagningar kan identifieras. Ungdomarna som påbörjar kontakt med mottagningen i Stockholm verkar ha problem av något lindrigare art jämfört med Göteborg och Malmö och utgör mindre andelar både när det gäller komplicerande bakgrundsfaktorer och nuvarande problembeteenden. Det finns även mindre skillnader i åldersstrukturen i de tre städerna, där Stockholm har fler ungdomar under 18 år medan både Göteborg och Malmö har fler som är över 18 år. Det finns även vissa könsskillnader genom att flickorna i samtliga tre städer tycks ha en tyngre problematik i jämförelse med pojkarna. Flickorna saknar i högre grad sysselsättning, anger oftare problem i skolan, har haft svårare uppväxtvillkor och har i större utsträckning haft kontakt med psykiatrin i jämförelse med pojkarna.Att sammanställa och rapportera deskriptiva indikatorer om individer som påbörjar behandling för alkohol- och narkotikaproblem kan ha flera fördelar. En sådan är att informationen kan ligga till grund för en ökad förståelse av ungdomars alkohol- och narkotikaanvändning och dess omfattning. Även om rapportens uppgifter inte är heltäckande, beskriver den en större population av svenska ungdomar med en problematisk användning av alkohol och droger. Föreliggande rapport är således en första ansats till att ge en sammanfattande bild av de ungdomar som påbörjar behandling vid Maria-mottagningarnas öppenvård i Stockholm, Göteborg och Malmö.
|
|
| 2. |
- Astromskas, Gvidas, et al.
(författare)
-
Temperature dependence of GaSb overgrowth of tungsten on GaSb (001) substrates using MOVPE
- 2008
-
Ingår i: 20th International Conference on Indium Phosphide and Related Materials, 2008. IPRM 2008. - 1092-8669. ; , s. 354-356
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate GaSb overgrowth over tungsten patterns and that selective area epitaxy is achievable in the W/GaSb system. By controlling the facet growth at low temperatures, it is possible to embed a metal grating in a thin layer.
|
|
| 3. |
- Astromskas, Gvidas, et al.
(författare)
-
Thin InAs membranes and GaSb buffer layers on GaAs(001) substrates
- 2012
-
Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 30:5
-
Tidskriftsartikel (refereegranskat)abstract
- Thin InAs layers and membranes are fabricated on GaAs substrates using GaSb buffer layers grown by MOVPE. The quality of the GaSb buffer layers is optimized and epitaxial InAs layers are grown on GaSb layers of various thickness. The best GaSb buffer layers are obtained for a nucleation temperature of 450 degrees C and a subsequent growth temperature of 570 degrees C with a V/III ratio of 3, as confirmed by both the structural (high-resolution XRD, AFM) and electrical (Hall) measurements. Furthermore, a clear relationship between the structural quality of the GaSb and InAs layers is established. Finally, free-standing InAs structures are fabricated where Hall measurements reveal a mobility that depends on the film thickness.
|
|
| 4. |
- Athle, Robin, et al.
(författare)
-
Effects of TiN Top Electrode Texturing on Ferroelectricity in Hf1-xZrxO2
- 2021
-
Ingår i: ACS applied materials & interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:9, s. 11089-11095
-
Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric memories based on hafnium oxide are an attractive alternative to conventional memory technologies due to their scalability and energy efficiency. However, there are still many open questions regarding the optimal material stack and processing conditions for reliable device performance. Here, we report on the impact of the sputtering process conditions of the commonly used TiN top electrode on the ferroelectric properties of Hf1-xZrxO2. By manipulating the deposition pressure and chemistry, we control the preferential orientation of the TiN grains between (111) and (002). We observe that (111) textured TiN is superior to (002) texturing for achieving high remanent polarization (Pr). Furthermore, we find that additional nitrogen supply during TiN deposition leads to >5× greater endurance, possibly by limiting the scavenging of oxygen from the Hf1-xZrxO2 film. These results help explain the large Pr variation reported in the literature for Hf1-xZrxO2/TiN and highlights the necessity of tuning the top electrode of the ferroelectric stack for successful device implementation.
|
|
| 5. |
- Athle, Robin, et al.
(författare)
-
Ferroelectric Tunnel Junction Memristors for In-Memory Computing Accelerators
-
Ingår i: Advanced Intelligent Systems. - 2640-4567.
-
Tidskriftsartikel (refereegranskat)abstract
- Neuromorphic computing has seen great interest as leaps in artificial intelligence (AI) applications have exposed limitations due to heavy memory access, with the von Neumann computing architecture. The parallel in-memory computing provided by neuromorphic computing has the potential to significantly improve latency and power consumption. Key to analog neuromorphic computing hardware are memristors, providing non-volatile multistate conductance levels, high switching speed, and energy efficiency. Ferroelectric tunnel junction (FTJ) memristors are prime candidates for this purpose, but the impact of the particular characteristics for their performance upon integration into large crossbar arrays, the core compute element for both inference and training in deep neural networks, requires close investigation. In this work, a W/HfxZr1−xO2/TiN FTJ with 60 programmable conductance states, a dynamic range (DR) up to 10, current density >3 A m−2 at V read = 0.3 V and highly nonlinear current–voltage (I–V) characteristics (>1100) is experimentally demonstrated. Using a circuit macro-model, the system level performance of a true crossbar array is evaluated and a 92% classification accuracy of the modified nation institute of science and technology (MNIST) dataset is achieved. Finally, the low on conductance in combination with the highly nonlinear I–V characteristics enable the realization of large selector-free crossbar arrays for neuromorphic hardware accelerators.
|
|
| 6. |
- Athle, Robin, et al.
(författare)
-
Impact of Temperature-Induced Oxide Defects on HfxZr1−xO2 Ferroelectric Tunnel Junction Memristor Performance
- 2023
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 70:3, s. 1412-1416
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we evaluate the importance of the postmetallization annealing (PMA) temperature on the performance of HfxZr1−xO2-based ferroelectric tunnel junctions (FTJs). Our results indicate a significant difference in tunneling electroresistance (TER) ratio and endurance, depending on the PMA temperature despite negligible variations in remanent polarization. We conclude that the minimization of conductive oxide defect states is central to achieve high performance. Through carefully optimized PMA conditions, we demonstrate FTJs with a TER = 3 and low mean cycle-to-cycle variation of < 1.5% combined with at least 16 separable conductance states providing a 4-bit resolution analog FTJ.
|
|
| 7. |
- Athle, Robin, et al.
(författare)
-
Improved Endurance of Ferroelectric HfxZr1–xO2 Integrated on InAs Using Millisecond Annealing
- 2022
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 9:27
-
Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric HfxZr1–xO2 (HZO) is typically achieved by crystallization of an amorphous thin film via rapid thermal processing (RTP) at time scales of seconds to minutes. For integration on III–V semiconductors, this approach can severely degrade the sensitive HZO/III–V interface. To evaluate whether a reduced thermal budget can improve the interface quality, millisecond duration thermal anneals are utilized using a flash lamp annealer (FLA) on HZO/InAs capacitors. Through thorough electrical characterization such as polarization hysteresis, endurance, and capacitance-voltage measurements, as well as synchrotron-based chemical interface characterization, the FLA and RTP treatments are compared and the FLA results are found in lower interface defect density and higher endurance, but also have generally lower remanent polarization (Pr) compared to RTP. Additionally, ways to achieve high Pr and low interface defect density using multiple lower energy flashes, as well as by pre-crystallization during the ALD growth step are investigated. Using FLA, Pr exceeding 20 µC cm−2 is achieved, with extended endurance properties compared to RTP treatment and a considerably decreased defect density, indicative of a higher quality HZO/InAs interface. This work presents valuable insight into the successful integration of ferroelectric HZO on low thermal budget III–V semiconductors.
|
|
| 8. |
- Athle, Robin, et al.
(författare)
-
Top Electrode Engineering for Freedom in Design and Implementation of Ferroelectric Tunnel Junctions Based on Hf1- xZrxO2
- 2022
-
Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 4:3, s. 1002-1009
-
Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric tunnel junctions (FTJs) based on ultrathin HfO2 have great potential as a fast and energy-efficient memory technology compatible with complementary metal oxide semiconductors. FTJs consist of a ferroelectric film sandwiched between two distinct electrodes, the properties of which are intricately linked to the electrical properties of the FTJs. Here we utilize a W crystallization electrode (CE) to achieve a high and reproducible remanent polarization, combined with a metal replacement process in which the W is carefully removed and replaced by another top electrode (TE). In this way we separate the ferroelectric film properties from the device design and can thereby evaluate the effect of the TE work function (WF) and conduction band electron density (ne) on the tunneling electroresistance (TER) and device reliability. We compare FTJs designed with a TiN bottom electrode and W, Cr, or Ni TE and find that the use of high electron density metals such as Ni or Cr as TE allows for an improved TER, albeit at the cost of reliability due to a large built-in electric field. To bypass this effect, a bilayer Cr/Ni TE is implemented, which allows for a high TER and minimal built-in field, leading to excellent retention and endurance beyond 108 cycles. The results presented here thus highlight a process flow for reliable design and implementation of FTJs.
|
|
| 9. |
- Berdnikov, Yury, et al.
(författare)
-
Broadening of length distributions of Au-catalyzed InAs nanowires
- 2016
-
Ingår i: State-of-the-Art Trends of Scientific Research of Artificial and Natural Nanoobjects, STRANN 2016: Proceedings of the 5th International Conference "State-of-the-Art Trends of Scientific Research of Artificial and Natural Nanoobjects". - : Author(s). - 9780735414051 ; 1748
-
Konferensbidrag (refereegranskat)abstract
- We investigate kinetic broadening effects on the length distributions of gold-catalyzed InAs nanowires having different diameters. It is shown that the length distributions acquire bimodal shape when the longest nanowires exceed the diffusion length of indium adatoms on the nanowire sidewalls. Later on, the length distributions recover unimodal shapes. We develop a theoretical model that is capable of describing the observed behaviors by accounting for the diffusion-induced character of the vapor-liquid-solid growth.
|
|
| 10. |
- Borg, Mattias
(författare)
-
Antimonide Heterostructure Nanowires - Growth, Physics and Devices
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Abstract in UndeterminedThis thesis investigates the growth and application of antimonide heterostructure nanowires for low-power electronics. In the first part of the thesis, GaSb, InSb and InAsSb nanowire growth is presented, and the distinguishing features of the growth are described. It is found that the presence of Sb results in more than 50 at. % group-III concentration in the Au seed particle on top of the nanowires. It is further concluded that the effective V/III ratio inside the seed particle is reduced compared to the outside. This enables the suppression of radial growth with remaining high axial growth rate. Furthermore, the low effective V/III ratio may affect the crystal structure formation, which is pure Zinc-blende in all investigated Sb-based nanowires. The strong segregating properties of Sb results in a strong Sb memory effect, and a difficulty to nucleate Sb-based nanowires directly on substrates.The second part of the thesis deals with the growth and application of GaSb/InAs(Sb) nanowires for tunnel device applications. The GaSb/InAs(Sb) nanowire heterojunction has a defect-free crystal structure with an extremely abrupt heterojunction due to an inherent delay before the initiation of InAs(Sb) growth. The Sb carry-over from the GaSb growth step into the InAs growth leads to a high Sb background in the InAs(Sb) segment. The diameter of the heterojunction can be reduced below 30 nm by an in-situ annealing treatment, in which material is selectively etched from the region near the heterojunction.The performance of GaSb/InAs(Sb) tunnel diodes is modeled and measured on fabricated single nanowire devices. The diodes exhibit peak current levels of 67 kA/cm^{2} , peak-to-valley current ratio between 2 and 3 at room temperature and a tunnel current at V_{D} = -0.5 V of 1.7 MA/cm^{2} . The expected performance of GaSb/InAs(Sb) tunnel field-effect transistors is discussed and preliminary measurement data on top-gated devices with 300 nm gate length is also presented.
|
|
