P-type silicon as hole supplier for nitride-based UVC LEDs

Abstract

The ineffective p-type doping of nitrides using magnesium (Mg), the best available dopant, has limited the development and performance of all III-nitride-based devices, including bipolar junction transistors and light emitting diodes (LEDs). For nitride-based ultraviolet (UV) LEDs, as the Al composition increases for achieving shorter wavelengths (e.g. <280 nm) into the UVC spectral range, the p-type doping issue, which causes very inefficient hole injection, becomes more severe than ever. In this work, we report the detailed study of using p-type Si as a hole supplier for high-Al composition UVC LEDs. We first describe the method of Si/GaN junction formation, where the lattice-mismatch challenge between Si and GaN is overcome by using a 0.5 nm thick Al 2 O 3 layer at the interface. This serves as a physical separation layer between the two materials as well as a passivation, tunneling, and thermal buffer layer. High-resolution transmission electron microscope image illustrates the highquality interface between Si and GaN. We further detail the hole transport mechanism of the p-p Si/ GaN isotype junction through both simulations and experiments. The enhanced hole concentration in the AlGaN/AlN multiple quantum wells (MQWs) due to the use of p-type Si as the hole supplier is verified through comparison with conventional UVC LEDs. Finally, high-performance UVC LEDs made with AlN/AlGaN (Al: 72%) MQWs employing p-type Si as their hole suppliers are demonstrated experimentally to serve as an example of the novel hole injector strategy.

Influences of ALD Al2O3 on the surface band-bending of c-plane, Ga-face GaN

“…rival those of the epitaxially grown, lattice-matched p-n junctions. Following the grafting approach [11], record-breaking III-nitride devices [12][13][14] and preliminary pnp AlGaAs/GaAs/Diamond HBT [15] have been reported. While the UO Al2O3 has been shown to play a critical role in the grafting method to achieve epitaxylike lattice-mismatched heterojunctions between good p-type semiconductors and n-type GaN, achieving GaN-collector heterojunction bipolar transistors (HBTs) via grafting is not straightforward unless proper band alignment is realized between the constituent materials.…”

“…rival those of the epitaxially grown, lattice-matched p-n junctions. Following the grafting approach, 11) record-breaking III-nitride devices [12][13][14] and preliminary pnp AlGaAs/GaAs/Diamond HBT 15) have been reported.…”

Vertical Field-Plated NiO/Ga2O3 Heterojunction Power Diodes

“…the Si and the β-Ga2O3. The role of the interface SiGaOx has served the identical roles in other grafted heterostructures where an ultrathin Al2O3 layer was applied using atomic layer deposition (ALD) [45,[54][55][56][57][58][59][60][61]. surface conditions.…”

Single‐Crystalline Ge1−xSnx/Si p–n Heterojunction Photodiodes with Sn Compositions up to 10%

“…Recently, germanium tin (GeSn)-based optoelectronic devices are gaining popularity in short wave infrared applications because of its high absorption coefficient and excellent spectral materials resulted from different lattice constants and thermal expansion coefficient by direct conformal contact via van der Waals force. [15][16][17][18][19][20][21][22][23] Therefore, it is worth exploring how the van der Waals bonding of Si and GeSn layers can form GeSn/Si heterojunctions.…”

“…For example, Si/Ge, Si/GaN, Ga 2 O 3 /GaN, Si/β‐Ga 2 O 3 , and Si/InGaAs heterojunctions alleviated the mismatch of the two dissimilar materials resulted from different lattice constants and thermal expansion coefficient by direct conformal contact via van der Waals force. [ 15–23 ] Therefore, it is worth exploring how the van der Waals bonding of Si and GeSn layers can form GeSn/Si heterojunctions.…”