PhD defence: Infrared Photodetectors based on InSb and InAs Nanostructures via Heterogeneous Integration-Rapid Melt Growth and Template Assisted Selective Epitaxy
Plats: E1406, E-huset, Ole Römers väg 3, LTH, Lund University, Lund, and online
Kontakt: heera [dot] menon [at] eit [dot] lth [dot] se
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Title: Infrared Photodetectors based on InSb and InAs Nanostructures via Heterogeneous Integration-Rapid Melt Growth and Template Assisted Selective Epitaxy
Author: Heera Menon, Department of Electrical and Information Technology, Lund University
Location: E1406 E-huset, Ole Römers väg 3, LTH, Lund University, Lund.
Link to thesis.
Monolithic heterogeneous integration of III-V semiconductors with the contemporary Si Complementary Metal Oxide Semiconductor (CMOS) technology has instigated a wide range of possibilities and functionalities in the semiconductor industry, in the field of digital circuits, optical sensors, light emitters, and high-frequency communication devices. However, the integration of III-V semiconductors is not trivial due to the differences in lattice parameters, polarity, and thermal expansion coefficient. This thesis explores two integration techniques to form III-V nanostructures with potential applications in the infrared detection field. The first technique implemented in this thesis work is the Rapid Melt Growth technique. InSb, which has a large lattice mismatch (19%) to Si, is used to demonstrate the RMG integration technique. A flash lamp with a millisecond annealing technique is utilized to melt and recrystallize amorphous InSb material to form a single crystalline material. The development of the fabrication process and the experimental results for obtaining a single crystalline InSb-on-insulator from a Si seed area through the RMG process are presented. Electron Back Scatter Diffraction (EBSD) technique was employed to understand the crystal quality, orientation, and defects in the RMG InSb nanostructures. The InSb nanostructures have a resistivity of 10 mΩ cm, similar to the VLS-grown InSb nanowires. Mobility ranging from 3490 - 877 cm2/ V sec was extracted through Hall and Van der Pauw measurements. Finally, we report the first monolithic integrated InSb nanostructure photodetector on Si through the RMG process. Detailed optical and electrical characterization of the device, including the spectrally resolved photocurrent and the temperature-dependent dark current, is studied. The thesis presents an InSb photodetector with a stable photodetector with a responsivity of 0.5 A/W at 16 nW illumination and millisecond time response. The second integration technique implemented in this thesis work is Template Assisted Selective Epitaxy. Here, the versatility of TASE technique to integrate InAs nanowires on W metal seed is demonstrated. This technique enables the feasibility of integrating III-V semiconductors to back -end of the line integration with Si CMOS technology. EBSD technique was utilized to study and obtain the statistics on the single crystalline InAs nanowires grown from different diameter templates. We also demonstrate the possibility of achieving an nBn InAs detector using TASE on W approach. This technique is a promising step towards developing high operating temperature (HOT) monolithic integrated mid-infrared detectors. Thus, the results of this thesis provide the perspective into two viable CMOS-compatible III-V integration techniques that could be utilized for photodetector applications at a reduced cost.