Superinjection of Holes in Homojunction Diodes Based on Wide-Bandgap Semiconductors

Abstract

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 n-type doped, 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 semiconductor 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 four orders of magnitude depending on the semiconductor material, dopant, and temperature, 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 nonclassical light sources based on color centers in SiC, AlN, ZnO, and other wide-bandgap semiconductors.

Single-Photon Sources Based on Novel Color Centers in Silicon Carbide P–I–N Diodes: Combining Theory and Experiment

“…1 . The donor compensation ratio by acceptor-type impurities and defects in the n-type regions and acceptor compensation ratio by donor-type impurities and defects in the p-type region are assumed to be 1% [ 28 ]. The thickness of the oxide layer on top of the n − -type region is 45 nm.…”

“…Most of these point defects in the crystal lattice of wide-bandgap semiconductors are free from blinking and bleaching and have a short radiative lifetime of the excited state. However, their electrical excitation is complicated due to the low density of free carriers in wide-bandgap semiconductors [27][28][29][30][31][32]. Meanwhile, electrical pumping is the only possibility to achieve high energy efficiency, integrability, and scalability of single-photon sources [10,[33][34][35].…”

Superinjection in Diamond p - i - n Diodes: Bright Single-Photon Electroluminescence of Color Centers Beyond the Doping Limit

“…2(b), one can see a flat-band p-region, while the band bending is strong in the i-and n-regions. The region of the potential well for electrons (potential barrier for holes) is a bridge between two regions with different types of conductivity (diffusion conductivity in the p-region and drift conductivity in the n-region) [39,40]. Due to the high asymmetry of the p-i-n structure, i.e., due to the huge difference in electrical properties of the ntype and p-type regions, the potential well is significantly deep at moderate and high bias voltages [40].…”

Optoelectronics of Color Centers in Diamond and Silicon Carbide: From Single‐Photon Luminescence to Electrically Controlled Spin Qubits

“…[140] Both activation energies are much lower than the activation energies of dopants in diamond, which gives the possibility to achieve much higher densities of free charge carriers in the i-region of the 4H-SiC p-i-n diode under high forward bias. [141,142] At the same time, the bandgap energies of the polytypes of silicon carbide are sufficiently high to host color centers emitting in the visible and near-infrared spectral regions. Since the electroluminescence process of the color center is driven by the electron and hole capture processes, the expected SPEL rate is also much higher than that from color centers in diamond.…”