Electrical and optical properties of heavily Ge-doped AlGaN
Electrical and optical properties of heavily Ge-doped AlGaN
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重Ge掺杂AlGaN的电学和光学特性
DOI：
10.1088/1361-6463/aafec2
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
E. Monroy
中科院分区：
文献类型：
--
作者：
R. Blasco;A. Ajay;E. Robin;C. Bougerol;K. Lorentz;L. Alves;I. Mouton;L. Amichi;A. Grenier;E. Monroy
我们报道了锗作为n型掺杂剂对等离子体辅助分子束外延生长的AlxGa 1 −xN层的电学和光学性质的影响。Al的含量从x = 0变化到0.66，通过卢瑟福背散射光谱法证实，Ge的浓度增加到[Ge] = 1 × 1021 cm−3。即使在这些高掺杂水平（>1%原子分数）下，Ge也不会在x < 0.15的AlxGa 1 −xN层中引起任何结构退化。然而，对于较高的Al组合物，观察到Ge形成微晶的聚集。霍尔效应测量显示，当增加Al摩尔分数时，载流子浓度逐渐降低，这在x = 0.24的样品中已经是明显的。x = 0.64-0.66的样品保持导电（σ = 0.8-0.3 Ω−1 cm−1），但施主激活率下降到约0.1%（载流子浓度约为1 × 1018 cm−3，[Ge]= 1 × 1021 cm−3）。从光学的角度来看，低温光致发光主要是由带到带的发射，它只显示与Burstein-Moss效应相关的光谱移动和加宽。光致发光峰位随温度的变化表明，Ge掺杂产生的自由载流子可以有效地屏蔽合金无序引起的电势起伏。
We report the effect of germanium as n-type dopant on the electrical and optical properties of AlxGa1−xN layers grown by plasma-assisted molecular-beam epitaxy. The Al content has been varied from x = 0 to 0.66, confirmed by Rutherford backscattering spectrometry, and the Ge concentration was increased up to [Ge] = 1 × 1021 cm−3. Even at these high doping levels (>1% atomic fraction) Ge does not induce any structural degradation in AlxGa1−xN layers with x < 0.15. However, for higher Al compositions, clustering of Ge forming crystallites was observed. Hall effect measurements show a gradual decrease of the carrier concentration when increasing the Al mole fraction, which is already noticeable in samples with x = 0.24. Samples with x = 0.64–0.66 remain conductive (σ = 0.8–0.3 Ω−1 cm−1), but the donor activation rate drops to around 0.1% (carrier concentration around 1 × 1018 cm−3 for [Ge] ≈ 1 × 1021 cm−3). From the optical point of view, the low temperature photoluminescence is dominated by the band-to-band emission, which shows only the spectral shift and broadening associated to the Burstein–Moss effect. The evolution of the photoluminescence peak position with temperature shows that the free carriers due to Ge doping can efficiently screen the potential fluctuations induced by alloy disorder.
影响因子：
3.4
作者：
Ajay, A.;Schoermann, J.;Monroy, E.
通讯作者：
Monroy, E.