Abstract:
With their tunable direct bandgaps, outstanding transport properties, and capability for band engineered heterostructures, III-V alloys are particularly well-suited for (opto)electronic devices operating across the electromagnetic spectrum. However, challenges remain in their integration in photonic and quantum systems due to limitations in direct growth on commercially available substrates and challenges in achieving seamless coupling to foreign, amorphous materials. In this talk, I will discuss emerging materials and growth techniques that can be realized by molecular beam epitaxy to overcome these challenges in monolithic integration.
First, I will discuss how highly mismatched alloys can be designed to decouple lattice parameter and band structure, enabling devices that operate at technologically significant wavelengths while lattice-matched to commercially available substrates. Although such alloys must be grown at extreme conditions to prevent desorption or surface segregation of the mismatched element, growing under a kinetically limited regime promotes highly substitutional incorporation and result in epilayers with excellent structural and optical quality. In particular, we will look at boron incorporation into InGaAs and bismuth incorporation into InAsSb for novel infrared photodetectors operating at extended wavelengths.
Then, I will discuss how selective area growth can be leveraged for the seamless integration of III-V alloys with dissimilar “mask” materials for a scalable approach to coupling active and passive devices. By enhancing adatom desorption and diffusion, polycrystalline nucleation on the mask can be mitigated so that growth only proceeds in open window between mask features. Historically, selective area growth has relied almost entirely on SiO2 and Si3N4 masks, limiting the applications and functionalities of integrated systems. Here, I will present an expansion to the palette of mask materials that can be successfully employed for III-V selective area growth, with focuses on thin amorphous carbon and ZrO2, as well as a generalized look at the underlying mechanisms that drive adatom desorption and diffusion on masks.
Bio: Corey White is an assistant professor in the Department of Electrical and Computer Engineering at Tufts University. Her research focuses on the integration of dissimilar materials and the synthesis of novel III-V semiconductors by molecular beam epitaxy for (opto)electronic applications. She received B.S. degrees in Electrical Engineering and Computer Engineering from North Carolina State University and M.S. and Ph.D. degrees in Electrical Engineering from the University of Texas at Austin. Prior to joining Tufts, she was a postdoctoral fellow at the University of Illinois Urbana-Champaign. She has been the recipient of an Early Career Author Award from Journal of Vacuum Science & Technology, an Illinois Distinguished Postdoctoral Fellowship, an NSF Graduate Research Fellowship, and has received four best paper awards at international conferences.
