Abstract
Combining Si-based integrated optics with Si-based microelectronics is crucial for next-generation applications ranging from data transfer on short distances to sensing and, potentially, to quantum cryptography at telecom wavelengths. However, Si's intrinsically poor light-emitting properties, i.e., its indirect energy bandgap, inhibit a straightforward implementation of telecom devices such as light-emitting diodes and lasers operating at room temperature.
We argue that adding Ge heterostructures, nanostructures, intentionally-induced defects, and defects within nanostructures to the Si platform can be a viable way to overcome the limitations of Si as a light-emitting material [1]. Significant progress for light-emission from group-IV nanostructures can be achieved by intentionally incorporating extended point defects inside the QDs upon in-situ low-energy ion implantation [2],[3]. This work discusses the superior light-emission properties from such defect-enhanced quantum dots (DEQDs) and our present understanding of their structural formation and light-emission mechanisms [4], indicating that optically direct recombination paths play a role in room-temperature light emission.
As compared to other group-IV systems with pronounced optical emission, contact doping and hence fabrication of electrically driven devices is relatively straightforward in this nanosystem since DEQDs are embedded into a defect-free Si matrix [5],[6]. We show that useful electrically driven devices, such as light-emitting diodes (LEDs), can be fabricated employing optically active DEQD material. These LEDs exhibit exceptional temperature stability of their light-emission properties even up to 100°C, unprecedented for purely group-IV-based optoelectronic devices [7]. We discuss the role of vital parameters, such as the temperature stability of the structural properties [8],[9], the scalability of the light-emission with the nanostructure density [6], and passivation schemes to further improve the optical properties [8],[10]. Additionally, we elaborate on schemes for advanced layouts for electrically-pumped devices.
References
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