20 research outputs found
Superinjection of holes in homojunction diodes based on wide-bandgap semiconductors
Electrically driven light sources are essential in a wide range of
applications, from indication and display technologies to high-speed data
communication and quantum information processing. Wide-bandgap semiconductors
promise to advance solid-state lighting by delivering novel light sources.
However, electrical pumping of these devices is still a challenging problem.
Many wide-bandgap semiconductor materials, such as SiC, GaN, AlN, ZnS, and
Ga2O3, can be easily doped n-type, but their efficient p-type doping is
extremely difficult. The lack of holes due to the high activation energy of
acceptors greatly limits the performance and practical applicability of
wide-bandgap semiconductor devices. Here, we study a novel effect which allows
homojunction semiconductors devices, such as p-i-n diodes, to operate well
above the limit imposed by doping of the p-type material. Using a rigorous
numerical approach, we show that the density of injected holes can exceed the
density of holes in the p-type injection layer by up to three orders of
magnitude, which gives the possibility to significantly overcome the doping
problem. We present a clear physical explanation of this unexpected feature of
wide-bandgap semiconductor p-i-n diodes and closely examine it in 4H-SiC,
3C-SiC, AlN and ZnS structures. The predicted effect can be exploited to
develop bright light emitting devices, especially electrically driven
non-classical light sources based on color centers in SiC, AlN, ZnO and other
wide-bandgap semiconductors.Comment: 6 figure
Electrical Charge State Manipulation of Single Silicon Vacancies in a Silicon Carbide Quantum Optoelectronic Device
Colour centres with long-lived spins are established platforms for quantum
sensing and quantum information applications. Colour centres exist in different
charge states, each of them with distinct optical and spin properties.
Application to quantum technology requires the capability to access and
stabilize charge states for each specific task. Here, we investigate charge
state manipulation of individual silicon vacancies in silicon carbide, a system
which has recently shown a unique combination of long spin coherence time and
ultrastable spin-selective optical transitions. In particular, we demonstrate
charge state switching through the bias applied to the colour centre in an
integrated silicon carbide opto-electronic device. We show that the electronic
environment defined by the doping profile and the distribution of other defects
in the device plays a key role for charge state control. Our experimental
results and numerical modeling evidence that control of these complex
interactions can, under certain conditions, enhance the photon emission rate.
These findings open the way for deterministic control over the charge state of
spin-active colour centres for quantum technology and provide novel techniques
for monitoring doping profiles and voltage sensing in microscopic devices
Bright Silicon Carbide Single-Photon Emitting Diodes at Low Temperatures: Toward Quantum Photonics Applications
Color centers in silicon carbide have recently emerged as one of the most promising emitters for bright single-photon emitting diodes (SPEDs). It has been shown that, at room temperature, they can emit more than 109 photons per second under electrical excitation. However, the spectral emission properties of color centers in SiC at room temperature are far from ideal. The spectral properties could be significantly improved by decreasing the operating temperature. However, the densities of free charge carriers in SiC rapidly decrease as temperature decreases, which reduces the efficiency of electrical excitation of color centers by many orders of magnitude. Here, we study for the first time the temperature characteristics of SPEDs based on color centers in 4H-SiC. Using a rigorous numerical approach, we demonstrate that although the single-photon electroluminescence rate does rapidly decrease as temperature decreases, it is possible to increase the SPED brightness to 107 photons/s at 100 K using the recently predicted effect of hole superinjection in homojunction p-i-n diodes. This gives the possibility to achieve high brightness and good spectral properties at the same time, which paves the way toward novel quantum photonics applications of electrically driven color centers in silicon carbide
Self-Heating and Cooling of Active Plasmonic Waveguides
Loss
compensation in plasmonic nanostructures gives a possibility
to avoid problems with strong absorption in the metal and design deep-subwavelength
optical components for practical applications. At the same time, pumping
required for creation of population inversion produces a huge amount
of waste heat, which can significantly increase the device temperature
and degrade its performance. Eventually, self-heating is becoming
a severe problem for active plasmonics, since it limits the maximum
achievable optical gain. Here we report a comprehensive study of heat
generation and transport in electrically pumped active plasmonic waveguides,
in which the SPP propagation losses are compensated by gain in the
adjacent semiconductor and present a strategy for their efficient
cooling