BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d4b0d70b4fb DTSTART:20240920T073000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:Elements Room SUMMARY:ICFO | KARUPPASAMY PANDIAN SOUNDARAPANDIAN CLASS:PUBLIC DESCRIPTION:Moore's law\, a longstanding guide for the semiconductor indust ry\, successfully predicted the exponential growth in computing power by d oubling transistor counts every two years. However\, recent challenges in maintaining this pace\, attributed to physical limitations\, energy consum ption\, and escalating costs\, have prompted a shift in focus towards two- dimensional (2D) materials in semiconductor technology. This thesis aims t o bridge the gap in understanding the complexities of incorporating 2D mat erials\, such as Graphene (Gr)\, Transition Metal Dichalcogenides (TMD)\, and hexagonal boron nitride (hBN)\, into Complementary Metal-Oxide-Semicon ductor CMOS platforms\, paving the way for innovative optoelectronic devic es with improved functionality to overcome these challenges.\nHigh-quality heterostructures:\nThis thesis investigates the crucial role of encapsula nts and substrates in Gr-based heterostructures\, highlighting their impac t on electronic transport characteristics\, such as hysteresis (∆n)\, ca rrier mobility (µ\;)\, and residual charge carrier concentration (n*) . Owing to the quality and integration complexity of scalable large-area t hick hBN\, this thesis explores the utilization of TMD-like tungsten disel enide (WSe2) and tungsten disulfide (WS2) as substrates and encapsulants\, respectively\, for Gr. The hybrid heterostructures fabricated with WSe2/G r/hBN and WS2/Gr/hBN exhibited a high µ\; of ~170\,000 and ~140\,000 cm2V-1s-1 with a n^*of ~7 and 8 x 1010 cm-2 respectively. This study under scores the significance of substrate engineering\, particularly for WS2. A successful demonstration of the effectiveness of TFSI-treated WS2 in enca psulating Gr and its role as a gate dielectric has been established. The t reated devices exhibited remarkable stability and resilience\, leading to a low ∆n of ~2 x 109 cm-2 with a µ\; of ~62\,000 cm2V-1s-1 and a n^ * of ~1.7 x 1011 cm-2. Waveguide-integrated photodetectorsThe exponential growth of internet users and data traffic necessitates higher bandwidth ca pabilities in communication systems. Optical transceivers play a pivotal r ole in meeting this demand\, particularly in data centers and broadband ac cess networks. This thesis focuses on the crucial components of optical tr ansceivers\, specifically photodetectors (PD)\, optimized for a wavelength of 1550 nm\, a standard for long-distance communication in optical fibers . This thesis explores a photothermoelectric (PTE) WSe2 encapsulated Gr ph otodetector on a waveguide to address this challenge. Up on a comprehensiv e analysis of the device's design\, the fabricated PD with different width s exhibited a responsivity up to ~12 V/W (long) or 0.1 A/W and ~32 mA/W or 18 V/W (short) with a setup limited bandwidth of 110 GHz. PDs also demons trated direct detection of NRZ and PAM-4 optical signals up to 120 and 160 Gbps\, respectively.\nWireless receivers:\nMeanwhile\, in wireless teleco mmunications\, efforts must be directed towards boosting data rates to acc ommodate growing data traffic\, as indicated by Edholm's law. The proposed 6G wireless devices are expected to achieve peak data rates of up to 1Tbp s. To overcome speed bottlenecks\, this thesis proposes exploring the tera hertz (THz) range\, with a focus on the sub-THz (~200GHz-300GHz) window\, exhibiting low-attenuation demands for short-range (<\;200m) wireless ap plications. We performed an extensive investigation and optimization of th e performance of a PTE-based Gr photodetector using various encapsulants. Among these\, the hBN-encapsulated Gr PDs exhibited superior performance c ompared to their counterparts (PD with CVD Gr)\, with an elevated responsi vity of ~240 (~30) V/W and low noise equivalent power (NEP) of ~1 (~9) x 1 0-11 W/&radic\;Hz. The fabricated PDs exhibited a bandwidth of approximate ly 1.9 GHz\, enabling data rates of 2 Gbps. Finally\, we developed a Gr-ba sed receiver\, establishing a sub-terahertz wireless communication link th at achieved data rates of up to 3 Gbps and efficiently operated over a dis tance of 2.5 meters. DTSTAMP:20260407T072303Z END:VEVENT END:VCALENDAR