Wangkheirakpam Vandana Devi
@iiitmanipur.ac.in
Assistant Professor, Electronics and Communication Engineering
Indian Institute of Information Technology Senapati Manipur
EDUCATION
Ph.D. in Semiconductor Devices from National Institute of Technology Silchar
M.Tech. in Microelectronics and VLSI Design from National Institute of Technology Silchar
RESEARCH INTERESTS
Semiconductor Devices, Sensors, Optoelectronics
Scopus Publications
Scopus Publications
Priyanshu Agrawal, Vandana Devi Wangkheirakpam, and Dhandapani Vaithiyanathan
IEEE
This paper studies the performance assessment of Hetero-Stacked Source Tunnel FET for greater responsiveness in biosensing application. The presence of Si stack over the Ge gives an improved drain current characteristic. This leads to the increase in the sensitivity up to the of 103. A comparative analysis of the TCAD simulated results of HS-TFET is made with conventional TFET based dual nanogap biosensor considering the measured sensitivity parameter. We can observe that sensitivity of HS-TFET Transistor Biosensor is of the order of 100 times that of sensitivity of C-TFET.
P. Ghosh, S. Tripathi, and W. V. Devi
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Nature Singapore
Dayananda Khwairakpam, Puspa Pukhrambam, and Vandana Wangkheirakpam
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
CRC Press
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
IEEE
This article reports a highly sensitive and low power photosensor using dual MOSCAP Vertical TFET for near infrared light detection in the wavelength range 0.7µm to 1µm. The optical voltage (VOP) developed because of the photogeneration occurring within the gate region enhances the gate control over the channel and produces higher drain current. The sensitivity is calculated by measuring the alteration of drain current with wavelength. Peak sensitivity of the order of 105 is obtained at VGS=0.5V and provides a maximum responsivity of 1.6x103 A/W at VGS=1.5V for λ= 0.7μm. This modified TFET based hybrid photosensor can be a new generation of highly sensitive photosensor.
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Elsevier BV
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
IEEE
This work reports the fundamental concepts on n+ pocket Vertical Tunnel FET (VTFET). An optimization strategy that is applicable to any TFET geometry is presented to optimize its electrical parameters. Furthermore, the optimized device geometry is tested for its reliability under non-ideal situation. Examination of device characteristics has been done considering impact of interface trap charges. Two types of trap charge distributions viz. uniform and Gaussian are taken into account. Temperature affectability is also studied to find out the range of operating temperature of the device. Finally, the RF characterization of the device is carried out to check its viability in high frequency applications.
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Science and Business Media LLC
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Institute of Electrical and Electronics Engineers (IEEE)
In this paper, optically gated Tunnel Field Effect Transistor (TFET), operating on the principle of band-to-band tunneling, is designed for sensing closely spaced spectral wavelengths (~100nm) in the near-infrared region of spectrum (1–<inline-formula> <tex-math notation="LaTeX">$0.7~\\mu \\text{m}$ </tex-math></inline-formula>) at low intensity of illumination (<inline-formula> <tex-math notation="LaTeX">$\\!< 1\\text{W}$ </tex-math></inline-formula>/cm<sup>2</sup>). A photogenerated voltage, gate charge and semi-conductor charge models have been respectively developed to illustrate device operation. A higher illumination current, lower threshold voltage, steeper sub-threshold swing (SS) and higher I<sub>ON</sub>/I<sub>OFF</sub> of the proposed device, under the incident radiation, makes it compatible for low power operation with optimum performance. This device achieved a high sensitivity of 26.52 by utilizing the advantages of TFETs. On being exposed to different concentrations of uniform and Gaussian interface traps, the performance comparison is observed in terms of I<sub>ON</sub>, I<sub>OFF</sub> and SS. Gaussian trap is more susceptible to device performance degradation. Further, the low both the cases, the <inline-formula> <tex-math notation="LaTeX">$\\text{S}_{ID}$ </tex-math></inline-formula> is in the range of 10<sup>−18</sup> to 10<sup>−16</sup> A<sup>2</sup>/Hz for all the considered trap concentrations which is comparatively low. Finally, the comparison of <inline-formula> <tex-math notation="LaTeX">$\\text{S}_{ID}$ </tex-math></inline-formula> of the proposed device with the published works is done.
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
IOP Publishing
In this work, a δ-doped dual MOS-capacitor (MOSCAP) (D-MOS) tunnel field effect transistor is proposed and investigated. The investigation has been carried out by varying the mole fraction of the SiGe δ-layer as well as by optimizing device dimensions like the effective oxide thickness, elevated channel thickness and epi-layer (thin intrinsic layer of the MOSCAP region) length and thickness. The optimized proposed device offers an ON current of 6.91 × 106 A µm-1, ION/IOFF of 4.83 × 108, average sub-threshold swing of 18.67 mV dec−1 and a maximum cut-off frequency of 1.28 × 109 Hz. Furthermore, the application of the proposed device as a near-infrared optical sensor is studied using a photosensitive gate. It is observed that the device can sense closely spaced spectral wavelengths (∼100 nm) in the near-infrared region of the spectrum (1–0.7 µm) at low intensity of illumination (<1 W cm−2). The peak spectral sensitivities of 4.67 × 103, 3.3 × 103 and 9.77 × 102 for the wavelength pairs (0.8 µm–0.7 µm), (0.9 µm–0.8 µm) and (1 µm–0.9 µm), respectively, are observed making it a highly sensitive optical sensor.
Wangkheirakpam Vandana Devi, Brinda Bhowmick, and Puspa Devi Pukhrambam
Institute of Electrical and Electronics Engineers (IEEE)
This article examines the performance of N+ pocket-doped vertical tunnel field-effect transistor (VTFET)-based label-free biosensors with the help of an analytical model developed for electrostatic potential, electric field, and drain current along with an extensive verification of the simulated device data. The model incorporates the effects of dielectric constant as well as charge and renders a generalized solution applicable for both neutral and charged biomolecules. Besides, the sensitivity has been analyzed by measuring the shift in drain current due to a change in the dielectric constant. It has been observed that the proposed sensor shows a large deviation in drain current, and hence, <inline-formula> <tex-math notation="LaTeX">${I}_{ \\mathrm{\\scriptscriptstyle ON}}$ </tex-math></inline-formula> can be used as an appropriate sensing parameter. The variations in the drain current and threshold voltage (<inline-formula> <tex-math notation="LaTeX">${V}_{th}$ </tex-math></inline-formula>) due to the impact of positive/negative charged biomolecules have also been studied. Extensive TCAD simulations have been performed to investigate the device performance when the nanogaps are fully filled, three-quarterly filled, half-filled, quarterly filled, and unequally filled. Furthermore, a comparison has been made with MOSFET-based biosensors.
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Institute of Electrical and Electronics Engineers (IEEE)
A comprehensive evaluation of sensitivity between double gate tunnel FET and n+ pocket doped vertical tunnel FET based label-free biosensors is reported in this work. Both the biosensors possess nanogaps on the left and right of the fixed dielectric (HfO2) which enhances the capture area of the biosensors. Comparison has been made on the TCAD simulation studies of their sensitivities considering neutral/charged biomolecules having different dielectric constants. The sensitivity of VB is found to be approximately 104 times the sensitivity of DB due to its current conduction in both vertical and lateral directions. Also, the effects of steric hindrance and irregular position of probes/receptors are analyzed to understand the non-ideal behavior of the sensors. Sensitivity is calculated from the simulated results for four different cases of partially filled nanogaps – decreasing, increasing, concave and convex profiles. It rises by about 5–7% when filled factor is increased from 40 to 66%. Finally, benchmarking of proposed VB is done against other published literature as it gives better result in terms of sensitivity.
Vandana Devi Wangkheirakpam, Brinda Bhowmick, and Puspa Devi Pukhrambam
Springer Science and Business Media LLC
Wangkheirakpam Vandana Devi and Brinda Bhowmick
Institution of Engineering and Technology (IET)
In this work, a device called pocket doped junctionless tunnel field-effect transistor (JL-TFET) for digital inverter application is proposed. The operation of this device is subjected to junctionless technique and initially it has an N+-N+-N+ structure. This device utilises a SiGe N+ pocket at the source side and a dual gate namely, fixed gate and control gate. By keeping the fixed gate voltage below its flat band voltage and varying the control gate from 0 to V
DD
, the device is converted from the N+-N+-N+ structure to P-I-N structure and operates like a tunnel field-effect transistor (TFET). The inclusion of N+ pocket gives an additional tunnelling path perpendicular to the gate-oxide thickness. A brief examination of the proposed device has been done on the impacts of the work-function variations of both the gate metals. A subthreshold swing of 43.6 mV/dec is obtained for fixed and control gate work-function of 5 and 4.5 eV, respectively. The proposed device gives the drain current of 5.7 × 10
-4
A approximately twice that of conventional JL-TFET. Further, an radio frequency analysis of the device is done for different parameters such as drain current (
I
D
), total gate capacitance (
C
gg
), transconductance (
g
m
) and cut-off frequency (
f
T
) and the outcomes are compared with conventional JL-TFET. The device is found to be suitable for high-frequency application. Lastly, it is applied on inverter circuit and its voltage transfer characteristics are studied.
Wangkheirakpam Vandana Devi and Brinda Bhowmick
IEEE
In this paper, an N+ hetero pocket doped Dual metal Vertical TFET is proposed. Due to an additional tunneling contribution to current along the body thickness of the device the proposed device offers larger ON current and steeper subthreshold slope (SS) as compare to conventional Tunnel FET. Here, the n+ pocket doping is incorporated near the gate source overlap region. Moreover, the pocket material is optimized with different bandgap materials. The dual metal gate (DMG) is used and compared with single material gate (SMG). Further, with an n+ layer at the p-source side, improvements in the device performance in terms of on-current (10−3A), subthreshold swing, SS (39mV/dec) are achieved. The proposed device is optimized for channel length, silicon body layer thickness, source doping engineering, gate dielectric material. Finally, the analog performance of the device is examined and found the device is suitable for high frequency application.