Polarization-Induced Hole Doping in Wide–Band-Gap Uniaxial Semiconductor Heterostructures

Abstract

Impurity-based p-type doping in wide-band-gap semiconductors is inefficient at room temperature for applications such as lasers because the positive-charge carriers (holes) have a large thermal activation energy. We demonstrate high-efficiency p-type doping by ionizing acceptor dopants using the built-in electronic polarization in bulk uniaxial semiconductor crystals. Because the mobile hole gases are field-ionized, they are robust to thermal freezeout effects and lead to major improvements in p-type electrical conductivity. The new doping technique results in improved optical emission efficiency in prototype ultraviolet light-emitting-diode structures. Polarization-induced doping provides an attractive solution to both p- and n-type doping problems in wide-band-gap semiconductors and offers an unconventional path for the development of solid-state deep-ultraviolet optoelectronic devices and wide-band-gap bipolar electronic devices of the future.

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…Non-conventional doping schemes such as 3D superlattice doping and polarizationassisted doping can potentially be used to significantly increase the p-doping concentration in high-Al-content Al x Ga 1−x N layers. [267] The issue of light extraction and hole transport might also be addressable through the use of interband tunnel junctions. [206] New device designs and material deposition approaches to manage the strain and polarization in UWBG heterostructures are also being explored with some initial success.…”

“…The projection uses the experimentally derived E C for GaN [59] as the baseline (corrected for the updated values of mobility and permittivity in the table), as this is the highest known E C for any GaN or SiC diode. These projections follow the method described in detail in Hollis and Kaplar, [60] and, to ensure a level playing field for all materials, [29,54] n (Si) below 80-85% Al; p (Mg deep) [54,97] ; polarization doping [355,356] Possible S donor [97] ; no good acceptor Polarization-induced 2DEG n type (Sn, Si, Ge donors) [357] ; no known acceptor n type (S donor); deep acceptors [98] Light to medium p type for N A < mid- [106,107] 2018: 38 mm. [105] 2018: 38 mm.…”

True-blue laser diodes with tunnel junctions grown monolithically by plasma-assisted molecular beam epitaxy

“…However, recent reports have shown that by exploiting the strong internal piezoelectric fields present in nitride heterostructures, it is possible to reduce the depletion width of the p-n junction and achieve the strong tunneling of carriers through such a structure. 22,23) For example, by inserting an InGaN well into the p-n junction region, it is possible to reduce the specific resistance of the junction to 10 −4 Ω·cm. 2,4) It was also demonstrated that by introducing GdN nanoislands, the tunneling through the midgap states inside the TJ was enhanced.…”

Hydrogen-surfactant-assisted coherent growth of GaN on ZnO substrate

“…Moreover, In the recent years, the topic of growing N-polar GaN with comparable high crystal quality to Ga-polar GaN has attracted much attention [98][99][100], due to the special advantages of N-polar thin films over Ga-polar ones [43,[101][102][103][104]. Mg, In and Si are used to assist to get rid of the disadvantages of the N-polar film growth on traditional sapphire and SiC substrates [99,105].…”