Abstract
Increasing the energy efficiency and reducing the footprint of on-chip photodetectors enable dense optical interconnects for emerging computational and sensing applications. While heterojunction phototransistors (HPTs) exhibit high energy efficiency and negligible excess noise factor, their gain-bandwidth product (GBP) has been inferior to that of avalanche photodiodes at low optical powers. Here, we demonstrate that utilizing type-II energy band alignment in an Sb-based HPT results in six times smaller junction capacitance per unit area and a significantly higher GBP at low optical powers. These type-II HPTs were scaled down to 2 μm in diameter and fully integrated with photonic waveguides on silicon. Thanks to their extremely low dark current and high internal gain, these devices exhibit a GBP similar to the best avalanche devices (∼270 GHz) but with one order of magnitude better energy efficiency. Their energy consumption is about 5 fJ/bit at 3.2 Gbps, with an error rate below 10−9 at −25 dBm optical power at 1550 nm. These features suggest new opportunities for creating highly efficient and compact optical receivers based on phototransistors with type-II band alignment.
| Original language | English (US) |
|---|---|
| Article number | 036106 |
| Journal | APL Photonics |
| Volume | 10 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 1 2025 |
Funding
This work was partially supported by ARO Award No. W911NF1810429, NIH Award No. R21EY029516, and the W.M. Keck Foundation Award. The fabrication made use of the NUFAB facility of Northwestern University\u2019s NUANCE Center, the Pritzker Nanofabrication Facility part of the Pritzker School of Molecular Engineering at the University of Chicago, which have received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (Grant No. NSF ECCS-1542205); the MRSEC program (Grant No. NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN, and the Center for Nanoscale Materials of Argonne National Laboratory. The use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We thank Moshe Dolejsi (the University of Chicago) and David Czaplewski (Argonne National Laboratory) for their help in optimizing the EBL processes and material etching. We thank Alan Prosser (Fermilab) for his help in the BER measurement and the gigaBERT system.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Computer Networks and Communications
