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Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices
1Department of Physics, OSED, Fujian Provincial Key Laboratory of Semiconductor Materials and Applications, Xiamen University, Xiamen, 361005, China.
Scientific Reports
|February 25, 2016
Summary
A new multidimensional Mg-doped superlattice (SL) structure significantly improves vertical hole conductivity in AlGaN SLs. This novel design reduces potential barriers and enhances hole concentration, paving the way for advanced deep ultraviolet devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Semiconductor Physics
Background:
- Conventional Mg-doped AlGaN superlattices (SLs) exhibit poor vertical hole conductivity due to significant potential barriers for holes.
- Enhancing hole transport is crucial for developing high-performance AlGaN-based electronic and optoelectronic devices, particularly for deep ultraviolet applications.
Purpose of the Study:
- To propose and investigate a novel multidimensional Mg-doped superlattice (SL) structure for enhanced vertical hole conductivity.
- To theoretically analyze the electronic structure and experimentally validate the improved conductivity in the new SL design.
Main Methods:
- First-principle electronic structure calculations were performed to analyze the densities of states (DOS) and potential barriers.
- Partial charge and decomposed DOS analyses were used to understand the underlying mechanisms of improved conductivity.
- Multidimensional Mg-doped AlGaN/AlGaN SLs were grown using metalorganic vapor-phase epitaxy (MOVPE).
- Electrical properties, including hole concentration and resistivity, were measured at room temperature and 100 K.
Main Results:
- The multidimensional SL structure exhibits more delocalized valence band states along the c-axis and a significantly reduced potential barrier compared to conventional SLs.
- Hole concentration is greatly enhanced within the barrier regions of the multidimensional SL.
- Experimental results show a hole concentration up to 3.5 × 10^18 cm⁻³ and a resistivity as low as 0.7 Ω·cm at room temperature.
- High hole concentration is maintained even at low temperatures (100 K), demonstrating robust performance.
Conclusions:
- The novel multidimensional Mg-doped AlGaN SL structure effectively enhances vertical hole conductivity by reducing potential barriers and increasing hole concentration.
- Stronger pz hybridization between Mg and N atoms is identified as the key mechanism for improved vertical conductance.
- This work represents a significant advancement for achieving high p-type conductivity in Al-rich AlGaN materials, essential for next-generation deep ultraviolet devices.
