Effect Of AlN Spacer In The Layer Structure On High Rf Performance GaN-Based HEMTs On Low Resistivity Silicon At K-Band Application

AlGaN/GaN High Electron Mobility Transistors (HEMTs) grown on Si substrate are emerging as an attractive devices for many RF applications. This is due to lower circuits realization cost and multifunction chips integration. In this study we investigate the effect of AlN spacer between AlGaN and GaN of a sub-micron gate (0.3 μm) AlGaN/GaN and AlGaN/AlN/GaN HEMTs on a Low Resistivity LR Si substrates on RF performance. We have observed an enhancement in RF performance fT and fMAX in the HEMT with of AlN spacer; (fT) was increased from 47 GHz to 55 GHz and (fMAX) was increased from 79 GHz to 121 GHz. This enhancement in performance is mainly due to the increase in the mobility in the channel and confinement of the carriers reducing Cgs, and delay τ under the gate. We believe this is the first RF study of this type as previous studies were based on the effects of the DC characteristic of the devices [1]

Electrical and physical characterization of the Al₂O₃/ <i>p</i>-GaSb interface for 1%, 5%, 10%, and 22% (NH₄)₂S surface treatments

In this work, the impact of ammonium sulfide ((NH&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;S) surface treatment on the electrical passivation of the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;/ &lt;i&gt;p&lt;/i&gt;-GaSb interface is studied for varying sulfide concentrations. Prior to atomic layer deposition of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, GaSb surfaces were treated in 1%, 5%, 10%, and 22% (NH&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;S solutions for 10 min at 295 K. The smallest stretch-out and flatband voltage shifts coupled with the largest capacitance swing, as indicated by capacitance-voltage (&lt;i&gt;CV&lt;/i&gt;) measurements, were obtained for the 1% treatment. The resulting interface defect trap density (&lt;i&gt;D&lt;/i&gt;&lt;sub&gt;it&lt;/sub&gt;) distribution showed a minimum value of 4 x 10&lt;sup&gt;12&lt;/sup&gt; cm&lt;sup&gt;-2&lt;/sup&gt;eV&lt;sup&gt;-1&lt;/sup&gt; at &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;v&lt;/sub&gt; + 0.27 eV. Transmission electron microscopy and atomic force microscopy examination revealed the formation of interfacial layers and increased roughness at the Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;/ &lt;i&gt;p&lt;/i&gt;-GaSb interface of samples treated with 10% and 22% (NH&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;S. In combination, these effects degrade the interface quality as reflected in the &lt;i&gt;CV&lt;/i&gt; characteristics

Effect Of AlN Spacer In The Layer Structure On High Rf Performance GaN-Based HEMTs On Low Resistivity Silicon At K-Band Application

AlGaN/GaN High Electron Mobility Transistors (HEMTs) grown on Si substrate are emerging as an attractive devices for many RF applications. This is due to lower circuits realization cost and multifunction chips integration. In this study we investigate the effect of AlN spacer between AlGaN and GaN of a sub-micron gate (0.3 μm) AlGaN/GaN and AlGaN/AlN/GaN HEMTs on a Low Resistivity LR Si substrates on RF performance. We have observed an enhancement in RF performance fT and fMAX in the HEMT with of AlN spacer; (fT) was increased from 47 GHz to 55 GHz and (fMAX) was increased from 79 GHz to 121 GHz. This enhancement in performance is mainly due to the increase in the mobility in the channel and confinement of the carriers reducing Cgs, and delay τ under the gate. We believe this is the first RF study of this type as previous studies were based on the effects of the DC characteristic of the devices [1]

(Invited) towards a vertical and damage free post-etch InGaAs fin profile: dry etch processing, sidewall damage assessment and mitigation options

Based on current projections, III-Vs are expected to replace Si as the n-channel solution in FinFETs at the 7nm technology node. The realisation of III-V FinFETs entails top-down fabrication via dry etch techniques. Vertical fins in conjunction with high quality sidewall MOS interfaces are required for high-performance logic devices. This, however, is difficult to achieve with dry etching. Highly anisotropic etching required of vertical fins is concomitant with increased damage to the sidewalls, resulting in the quality of the sidewall MOS interface being compromised. In this work, we address this challenge in two stages by first undertaking a systematic investigation of dry etch processing for fin formation, with the aim of obtaining high resolution fins with vertical sidewalls and clean etch surfaces. In the second stage, dry etch process optimisation and post-etch sidewall passivation schemes are explored to mitigate the damage arising from anisotropic etching required for the realisation of vertical fins

The impact of forming gas annealing on the electrical characteristics of sulfur passivated Al2O3/In0.53Ga0.47As (110) metal-oxide-semiconductor capacitors

This study reports the impact of forming gas annealing (FGA) on the electrical characteristics of sulfur passivated, atomic layer deposited Al2O3 gate dielectrics deposited on (110) oriented n- and p-doped In0.53Ga0.47 As layers metal-oxide-semiconductor capacitors (MOSCAPs). In combination, these approaches enable significant Fermi level movement through the bandgap of both n- and p-doped In0.53Ga0.47 As (110) MOSCAPs. A midgap interface trap density (Dit) value in the range 0.87−1.8×1012 cm−2eV−10.87−1.8×1012 cm−2eV−1 is observed from the samples studied. Close to the conduction band edge, a Dit value of 3.1×1011 cm−2eV−13.1×1011 cm−2eV−1 is obtained. These data indicate the combination of sulfur pre-treatment and FGA is advantageous in passivating trap states in the upper half of the bandgap of (110) oriented In0.53Ga0.47 As. This is further demonstrated by a reduction in border trap density in the n-type In0.53Ga0.47 As (110) MOSCAPs from 1.8×1012 cm−21.8×1012 cm−2 to 5.3×1011 cm−25.3×1011 cm−2 as a result of the FGA process. This is in contrast to the observed increase in border trap density after FGA from 7.3×1011 cm−27.3×1011 cm−2 to 1.4×1012 cm−21.4×1012 cm−2 in p-type In0.53Ga0.47 As (110) MOSCAPs, which suggest FGA is not as effective in passsivating states close to the valence band edge

The effect of statins on muscle symptoms in primary care:the StatinWISE series of 200 N-of-1 RCTs

Background: Uncertainty persists about whether or not statins cause symptomatic muscle adverse effects (e.g. pain, stiffness and weakness) in the absence of severe myositis.Objectives: To establish the effect of statins on all muscle symptoms, and the effect of statins on muscle symptoms that are perceived to be statin related.Design: A series of 200 double-blinded N-of-1 trials.Setting: Participants were recruited from 50 general practices in England and Wales.Participants: Patients who were considering discontinuing statin use and those who had discontinued statin use in the last 3 years because of perceived muscle symptoms.Interventions: Participants were randomised to a sequence of six 2-month treatment periods during which they received 20 mg of atorvastatin daily or a matched placebo.Main outcome measures: The primary outcome was self-reported muscle symptoms rated using a visual analogue scale on the last week of each treatment period. Secondary outcomes included the participant's belief about the cause of their muscle symptoms, the site of muscle symptoms, how the muscle symptoms affected the participant, any other symptoms they experienced, adherence to medication, the participant's decision about statin treatment following the trial, and whether or not they found their own trial result helpful.Results: A total of 151 out of 200 (75.5%) randomised participants provided one or more visual analogue scale measurements in a placebo period and one or more measurements in a statin period, and were included in the primary analysis. There was no evidence of a difference in muscle symptom scores between statin and placebo periods (mean difference statin minus placebo -0.11, 95% confidence interval -0.36 to 0.14; p = 0.398). Withdrawals, adherence and missing data were similar during the statin periods and the placebo periods.Conclusions: Among people who previously reported severe muscle symptoms while taking statins, this series of randomised N-of-1 trials found no overall effect of statins on muscle symptoms compared with the placebo. The slight difference in withdrawals due to muscle symptoms suggests that statins may contribute to symptoms in a small number of patients. The results are generalisable to patients who are considering discontinuing or have already discontinued statins because of muscle symptoms, and who are willing to re-challenge or participate in their own N-of-1 trial.Future work: We recommend that additional statins and doses are explored using N-of-1 trials. More broadly, N-of-1 trials present a useful tool for exploring transient symptoms with other medications.Limitations: This study used 20-mg doses of atorvastatin only. Furthermore, a dropout rate of 43% was observed, but this was accounted for in the power calculations.Trial registration: Current Controlled Trials ISRCTN30952488 and EudraCT 2016-000141-31.</p

Statin treatment and muscle symptoms:series of randomised, placebo controlled n-of-1 trials

OBJECTIVE: To establish the effect of statins on muscle symptoms in people who had previously reported muscle symptoms when taking statins. DESIGN: Series of randomised, placebo controlled n-of-1 trials. SETTING: Primary care across 50 sites in the United Kingdom, December 2016 to April 2018. PARTICIPANTS: 200 participants who had recently stopped or were considering stopping treatment with statins because of muscle symptoms. INTERVENTIONS: Participants were randomised to a sequence of six double blinded treatment periods (two months each) of atorvastatin 20 mg daily or placebo. MAIN OUTCOME MEASURES: At the end of each treatment period, participants rated their muscle symptoms on a visual analogue scale (0-10). The primary analysis compared symptom scores in the statin and placebo periods. RESULTS: 151 participants provided symptoms scores for at least one statin period and one placebo period and were included in the primary analysis. Overall, no difference in muscle symptom scores was found between the statin and placebo periods (mean difference statin minus placebo -0.11, 95% confidence interval -0.36 to 0.14; P=0.40)). Withdrawals because of intolerable muscle symptoms were 18 participants (9%) during a statin period and 13 (7%) during a placebo period. Two thirds of those completing the trial reported restarting long term treatment with statins. CONCLUSIONS: No overall effect of atorvastatin 20 mg on muscle symptoms compared with placebo was found in participants who had previously reported severe muscle symptoms when taking statins. Most people completing the trial intended to restart treatment with statins. N-of-1 trials can assess drug effects at the group level and guide individual treatment. TRIAL REGISTRATION: ISRCTN30952488, EUDRACT 2016-000141-31, NCT02781064

(Invited) The inversion behaviour of narrow band gap MOS systems: experimental observations, physics based simulations and applications

Impedance spectroscopy of the metal-oxide semiconductor (MOS) system has played a central role in the development of silicon-based complementary MOS (CMOS) technology over the past 50 years [1, 2]. With current research interest into alternative semiconductor channels to silicon for MOSFET and tunnel FET technologies, the measurement and interpretation of the overall impedance of the MOS structure requires detailed analysis to separate and quantify the contribution of interface states, and near interface traps (border traps), on the capacitance and conductance response, and to separate the contribution of these electrically active defect states from the ac response of minority carriers in the case of genuine inversion of the semiconductor/dielectric interface

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial