Anuj K. Sharma

Simulated characteristics of a heterojunction phototransistor with Ge1-xSnx alloy as base

Abstract. Groups III-V compound semiconductors and their alloys are the main photodetecting elements for the entire fiber optic telecommunication band. However, the recent successful growth of Ge1-xSnx alloy on Ge virtual substrates on Si platform makes the group IV alloys a potential competitor. Ge1-xSnx alloy shows direct band gap and has an absorption coefficient almost 10 times higher than that of Ge. The photonic devices are complementary metal–oxide–semiconductor compatible. We have considered an n-Ge/p+-Ge1-xSnx/n-Ge1-xSnx heterojunction phototransistor (HPT) and studied the variations of terminal currents by considering the Gummel Poon model of HPT, and values of optical and current gains, photocurrent, and responsivity have been obtained. The performance of the device as a photodetector at fiber optic communication wavelengths seems quite encouraging to justify the use of GeSn-based HPTs as a replacement of III-IV semiconductor-based photodetectors.

Co-creation as a risk-sharing strategy for the development of innovative EUV lithography technology in the semiconductor industry

Co-creation is becoming an innovative way for new technology development (NTD). We propose a four-staged co-creation model drawn upon a backdrop of ‘knowledge cloud’ for value creation and long-term customer commitment resulting in risk-sharing associated with NTD. The model is elaborated through the case of a leading semiconductor lithography equipment manufacturer (ASML) developing a new extreme ultraviolet lithography technology by engaging the major stakeholders in customer co-investment programme. The model is generic and applicable to any technology-driven industry and may include more stakeholders of same or allied technology.

Characteristics of heterojunction phototransistors with Ge 1−x Sn x multiple quantum wells in the base

Germanium-tin alloy (Ge<inf>1−x</inf>Sn<inf>x</inf>), due to its direct gap nature for x > 0.08, has higher absorption coefficient than that of pure Ge. Using COMSOL Multiphysics, we have simulated the characteristics of Ge/GeSn/Ge heterojunction phototransistor, the base of which incorporates a multiple quantum well (MQW) structure made of Ge<inf>0.87</inf>Sn<inf>0.13</inf> barrier and Ge<inf>0.75</inf>Sn<inf>0.155</inf> well at a wavelength of 1.55 μm. The 3-QW structure shows high current gain over a wider range of base-emitter voltage than a single QW structure and a structre without any QW.

Plasmonics-Based Fiber Optic Sensors

Since the unveiling of optical fiber technology in the field of plasmonics-based optical sensors, a lot of advancements have been witnessed. This chapter discusses a detailed mechanism of the technique of surface plasmon resonance (SPR) applied in optical fiber sensors. Some selected research works in the area of plasmonics-based fiber optic sensors reported in last 25–30 years along with future scope of work are also discussed.

On the performance of graphene based plasmonic biosensor with bimetallic combination on 2S2G prism

Surface plasmon resonance (SPR) sensors based on bimetallic combination of silver (Ag) and gold (Au) with grapheme in visible and in near infrared (IR) region of operation are studied. Five-layer sensors geometry is considered based on Kretschmann configuration having chalcogenide prism as substrate material. Proposed structure shows enhanced detection accuracy and intrinsic sensitivity at near IR wavelength.

AlN substrate based plasmonic sensor for saline water temperature determination

Aluminum Nitride (AlN) substrate possesses noble physical and optical properties at large ranges of wavelength and temperature. A new design of AlN-based surface plasmon resonance (SPR) sensor for investigation of the saline water temperature is proposed. Recent experimental results describing variation of refractive index of AlN with wavelength and temperature are considered for theoretical calculations. The angular interrogation method along with thermo-optic effect in metal and dielectric media is considered. The sensor’s performance is closely analyzed in terms of well-defined performance indicators in order to achieve reliable and accurate sensing performance. The influence of operating wavelength on the performance of temperature sensor is investigated. The proposed AlN-based temperature sensor has the capability to provide high performance. The stability of AlN at higher temperature is another advantage that contributes to precise measurements even at higher temperatures with AlN-based SPR sensor. High refractive index of AlN with SPR can make it a potential candidate for infrared sensing.

Investigation of CaF 2 substrate based plasmonic gas sensor in IR

The performance of proposed surface plasmon resonance based methane gas sensor based on Kretschmann configuration in infrared (IR) is discussed. In this structure, calcium fluoride (CaF2) substrate is considered with gold (Au) layer deposited on its base and methane gas is used as a sensing layer. Performance of sensor is analysed in terms of sensitivity and figure of merit (FOM) with various metal layer thicknesses using angular interrogation method.