Surface Treatments to Reduce Leakage Current in Homojunction In0:53Ga0:47As PIN Diodes for TFET Applications

In the field of low power electronics, Tunnel field-effect transistors (TFETs) are gaining momentum due to aggressive voltage scaling. To enable scaling of power supply while maintaining a high Ion, a steep subthreshold slope and low I0 are required. A TFET operates as a gated PIN diode under reverse bias with the intrinsic region as the channel. This study focuses on minimizing I0 in a III-V homojunction PIN diode. I0 or leakage current is the current owing in a PIN diode under reverse bias, that forms the o-state current (Vgate = 0 V) in a TFET. Various surface treatment combinations were performed to study surface leakage, of which, BCB and HCl were the most eective passivation and clean, respectively. For the first time, in this study, electrical characterization of sub-micron PIN diodes was performed

\tau Polarization asymmetry in B→Xsτ+τ−B \to X_s \tau^+ \tau^- in SUSY models with large tanβtan\beta

Rare B decays provides an opportunity to probe for new physics beyond the standard model. the effective Hamiltonian for the decay $b \to s l^+ l^-$ predicts the characteristic polarization for the final state lepton. Lepton polarization has, in addition to a longitudinal component $P_L$, two orthogonal components $P_T$ and $P_N$ lying in and perpendicular to the decay plane. In this article we perform a study of the $\tau$-polarisation asymmetry in the case of SUSY models with large $\tan\beta$ in the inclusive decay $B \to X_s \tau^+ \tau^-$.Comment: RevTex file, 15 pages (including 6 ps figures). accepted version in Phys. Rev.

Longitudinal Polarization in KL→μ+μ−K_L \to \mu^+ \mu^- in MSSM with large tanβtan\beta

A complete experiment on decay $K_L \to l^+ l^-$ will not only consist of measurement of the decay rates but also lepton polarization etc. These additional observations will yield tests of CP invariance in these decays. In $K_L$ and $K_S$ decays, the e mode is slower than the $\mu$ mode by roughly $(m_e/m_\mu)^2$ \cite{sehgal1}. As well discussed in literature \cite{herczeg} the Standard Model contribution to the lepton polarization is of order $2 \times \sim 10^{-3}$. We show that in MSSM with large \tanbeta and light higgs masses ($\sim 2 M_W$), the longitudinal lepton polarization in $K_L \to \mu^+ \mu^-$ can be enhanced to a higher value, of about $10^{-2}$.Comment: version appeared in Physics Letters B, minor correction

Utjecaj pandemije COVID-19 i karantene na anksioznost u starijoj populaciji: presječna studija

Background: The coronavirus pandemic is an epidemiological and psychological crisis. The elderly population is considered to be high risk for potential complications arising from the COVID-19 pandemic, and this fact can also potentially lead to anxiety symptoms amongst the elderly. Therefore, a study was conducted to assess the anxiety symptoms in elderly living in few major cities of Rajasthan state in India. Methods: The study was conducted from April 2020 to May 2020 using an online questionnaire which measured the levels of anxiety amongst the elderly population (age ≥ 65 years) living in the community via the GAD-7 (General Anxiety Disorder-7) scale. Responses were received from 162 participants. Data were analyzed using the Chi-square test and logistic regression. The level of statistical significance was kept at p value < 0.05. Results: Around 69.14% of the participants belonged to the age group of 65 -74 years; 61.72% of whom were male. Moreover, up to 82.72% of the participants were suffering from one or more chronic medical illnesses. Based on the GAD-7 scores, 30.25%, 12.35%, and 6.17% of the respondents were suffering from mild, moderate, and severe forms of anxiety, respectively. After applying a ≥ 5 score as a cut off score for the GAD-7 scale, 48.77% of the elderly participants were experiencing anxiety symptoms indicating further assessment. In those respondents with anxiety symptoms, significant association was observed with age (p = 0.00), sex (p = 0.04), and the zone of residence (p = 0.00). On the other hand, no significant association was observed with the presence of chronic medical illness such as Diabetes, Hypertension, COPD, etc. with anxiety symptoms (p = 0.77). Conclusion: This study has revealed a high prevalence of anxiety symptoms among the elderly population during the COVID-19 pandemic lock down. We recommend that a pre-planned strategy should be prepared for early identification of vulnerable elderly in the community who are at a greater risk of suffering from anxiety disorder under this stressful period.Pozadina: Pandemija koronavirusa epidemiološka je i psihološka kriza. Starija populacija smatra se visoko rizičnom za potencijalne komplikacije koje proizlaze iz pandemije COVID-19, što također može dovesti do simptoma anksioznosti kod starijih osoba. Stoga je provedeno istraživanje za procjenu simptoma anksioznosti kod starijih osoba koje žive u nekoliko većih gradova države Rajasthan u Indiji. Metode: Studija je provedena od travnja 2020. do svibnja 2020. godine korištenjem online upitnika koji je mjerio razine anksioznosti među starijom populacijom (dob ≥ 65 godina) koja živi u zajednici a putem skale GAD-7 (GAD-7 skala anksioznosti). Odgovori su dobiveni od 162 sudionika. Podaci su analizirani pomoću Chi-kvadrat testa i logističke regresije. Razina statističke značajnosti zadržana je na vrijednosti p <0,05. Rezultati: Otprilike 69,14% sudionika pripadalo je dobnoj skupini od 65 do 74 godine; od kojih su 61,72% bili muškarci. Štoviše, do 82,72% sudionika patilo je od jedne ili više kroničnih medicinskih bolesti. Na temelju ocjena GAD-7, 30,25%, 12,35%, odnosno 6,17% ispitanika patilo je od blagog, umjerenog i teškog oblika anksioznosti. Nakon davanja ocjene ≥ 5 kao granične vrijednosti za GAD-7 ljestvicu, 48,77% starijih sudionika imalo je simptome anksioznosti što ukazuje na potrebu daljnje procjene. U ispitanika sa simptomima anksioznosti uočena je značajna povezanost s dobi (p = 0,00), spolom (p = 0,04) i zonom boravka (p = 0,00). S druge strane, nije uočena značajnija povezanost prisutnosti kroničnih medicinskih bolesti poput dijabetesa, hipertenzije, KOPB-a itd. sa simptomima anksioznosti (p = 0,77). Zaključak: Ova studija je otkrila visoku prevalenciju simptoma anksioznosti među starijom populacijom tijekom karantene izazvane pandemijom COVID-19. Preporučujemo pripremu unaprijed planirane strategije za ranu identifikaciju ranjivih starijih osoba u zajednici koje imaju veći rizik razvoja anksioznog poremećaja u ovom stresnom razdoblju

Understanding Charge Behaviour in a 2D Transition Metal Dichalcogenide MOS System

Advancements in technology are driven by downscaling the channel length and the thickness of semiconductor that improve performance of a MOSFET. 2D semiconductors, like transition metal dichalcogenides (MX2), are van der Waals (vdW) layered structures with one layer approx. 0.7 nm thick and self-terminated surfaces with no dangling bonds. They offer the promise of ultrathin channels with high mobility for future technology nodes. 2D materials have a wide range of physical and chemical properties, which has also generated keen interest in the sensors and display technology communities. However, in reality, material quality, processing issues and non-ohmic contacts have resulted in sub-standard performance of 2D MOSFETs. It is compounded by an inaccurate understanding of electrostatics and charge transport in the channel. In this thesis, we investigate a fundamental aspect of any 2D transistor – the oxide-semiconductor interface. Using MOS admittance spectroscopy, we inspect interface and oxide defects (Dit and Nbt, respectively) in MoS2 flakes and MOCVD grown MoS2 and WS2. We propose a new electrical test structure, called the edge MOS capacitor, which can probe defect states in the MX2 bandgap. Due to its design, MOS admittance characteristics become very sensitive to the channel length of the edge MOS capacitor (Lch) and the in-plane channel resistance (Rch). Using the Silicon MOS capacitor model results in an overestimation of Dit as it does not factor the Lch and Rch dependence. Therefore, we develop a new MX2 MOS capacitor model with 2D electrostatics in DC and a distributed network in the AC regime. Using this, we study the strong coupling between Rch and vertical gate electrostatics in an edge MOS capacitor structure. We find that true Dit can be extracted only from short channel devices, while long channel devices are useful to evaluate electron/hole mobility. Using this an exponentially decaying Dit from the conduction band edge is found at the MoS2-HfO2 and MoS2-SrTiO3 interface. We also find that the maximum charge density (in accumulation) is limited by interfacial residues at the oxide-semiconductor interface. To boost channel performance, we investigate top and dual gate devices using MOCVD MoS2 and WS2. The true potential of a dual gate device can be realised in a scaled top and bottom gate configuration. We also observed hole transport in dual gate WS2 grown on SiO2 with edge contacts, paving way for ambipolar an p-type FETs using 2D materials.status: publishe