Modeling and Simulations of 4H-SiC/6H-SiC/4H-SiC Single Quantum-Well Light Emitting Diode Using Diffusion Bonding Technique

In the last decade, Silicon carbide (SiC) has emerged as a potential material for high-frequency electronics and optoelectronics applications that may require elevated temperature processing. SiC exists in more than 200 different crystallographic forms, referred to as polytypes. Based on their remarkable physical and electrical characteristics, such as better thermal and electrical conductivities, 3C-SiC, 4H-SiC, and 6H-SiC are considered as the most distinguished polytypes of SiC. In this article, physical device simulation of a light-emitting diode (LED) based on the unique structural configuration of 4H-SiC and 6H-SiC layers has been performed which corresponds to a novel material joining technique, called diffusion welding/bonding. The proposed single quantum well (SQW) edge-emitting SiC-based LED has been simulated using a commercially available semiconductor device simulator, SILVACO TCAD. Moreover, by varying different design parameters, the current-voltage characteristics, luminous power, and power spectral density have been calculated. Our proposed LED device exhibited promising results in terms of luminous power efficiency and external quantum efficiency (EQE). The device numerically achieved a luminous efficiency of 25% and EQE of 16.43%, which is at par performance for a SQW LED. The resultant LED structure can be customized by choosing appropriate materials of varying bandgaps to extract the light emission spectrum in the desired wavelength range. It is anticipated that the physical fabrication of our proposed LED by direct bonding of SiC-SiC wafers will pave the way for the future development of efficient and cost-effective SiC-based LEDs.

Investigation of SiGeSn/GeSn/SiGeSn single quantum well with enhanced well emission

In this work, a SiGeSn/GeSn/SiGeSn single quantum well was grown and characterized. The sample has a thicker GeSn well of 22 nm compared to our previously reported 9-nm well configuration. The thicker well leads to: i) lowered ground energy level in Γ valley offering more bandgap directness; ii) increased carrier density in the well; and iii) improved carrier collection due to increased barrier height. As a result, significantly enhanced emission from the quantum well was observed. The strong photoluminescence signal allows for the estimation of quantum efficiency, which was unattainable in previous studies. Using pumping-power-dependent photoluminescence spectra at 20 K, the peak spontaneous quantum efficiency and external quantum efficiency were measured as 37.9% and 1.45%, respectively.

Electron–electron scattering rate in CdTe/CdMnTe single quantum well

CdMnTe is demonstrated to be a good candidate in the X-ray and [Formula: see text]-ray detector application, however, there are few reports on theoretical analysis of electron scattering rate in CdMnTe quantum well. Within the framework of effective mass approximation and envelope function approximation, the influence of the Mn alloy composition ([Formula: see text], the well width ([Formula: see text], the electron temperature ([Formula: see text] and the electron density ([Formula: see text] on the electron–electron scattering rate (1/[Formula: see text] in the CdTe/Cd[Formula: see text]Mn[Formula: see text]Te single quantum well (SQW), are simulated by shooting method and Fermi’s Golden Rule. The results show that 1/[Formula: see text] is significant inverse proportional to [Formula: see text], but positively proportional to [Formula: see text] and [Formula: see text]. Except for a small peak at 20 K, 1/[Formula: see text] is not sensitive to [Formula: see text]. The above differential dependency of 1/[Formula: see text] on [Formula: see text] and [Formula: see text] can be interpreted by sub-band separation ([Formula: see text], which is proportional to [Formula: see text] but inversely proportional to [Formula: see text]. When [Formula: see text] decreases gradually, the electron transition becomes easier, which leads to 1/[Formula: see text] increases. The dependency of 1/[Formula: see text] on [Formula: see text] can be interpreted by kinetic energy of electrons. The larger the electron kinetic energy is, the more difficult the electron transition from first excited state to ground state is, which leads to 1/[Formula: see text] decreasing. The dependency of 1/[Formula: see text] on [Formula: see text] can be interpreted by the Coulomb interaction between electrons, i.e., the increase of electron collision probability caused by the increase of [Formula: see text].

Photoluminescence properties of GaAsBi single quantum wells with 10% of Bi

A set of single quantum well (SQW) samples of GaAs1-xBix with x ~ 0.1 and p-doped GaAs barriers grown by molecular beam epitaxy was investigated by the temperature-dependent photoluminescence (PL) spectroscopy. Those GaAsBi SQW structures showed a high crystalline quality, a smooth surface and sharp interfaces between the layers and exhibited a high PL intensity and a lower than 100 meV PL linewidth of QW structures. Temperature dependence of the optical transition energy was S-shape-free for all investigated structures and it was weaker than that of GaAs. An analysis of the carrier recombination mechanism was also carried out indicating that the radiative recombination is dominant even at room temperature. Moreover, numerical calculations revealed that a higher Be doping concentration leads to an increased overlap of the electron and heavy hole wave functions and determines a higher PL intensity.