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北京大学物理学院 人工微结构和介观物理国家重点实验室 北京,100871
收稿日期:2009-02-25,
修回日期:1900-01-02,
网络出版日期:2009-12-30,
纸质出版日期:2009-12-30
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于 涛, 李 睿, 杨子文, 等. Mg掺杂的AlxGa1-xN/GaN超晶格紫外峰的性质[J]. 发光学报, 2009,30(6):792-796.
YU Tao, LI Rui, YANG Zi-wen, et al. Ultraviolet Luminescence from Mg-doped AlxGa1-xN/GaN Superlattice[J]. Chinese journal of luminescence, 2009, 30(6): 792-796.
观测了不同Mg含量的Al
x
Ga
1-x
N/GaN超晶格(SLs)样品在不同退火温度和激发强度下的光致发光(PL)光谱。结合霍尔测量
分析了其紫外发射(UVL)峰的起源及相关影响因素。实验发现:同一样品在N
2
气氛中高温退火
UVL峰强随退火温度的升高
先增至饱和继而急剧下降
峰位红移;而在相同退火条件下
随着掺杂Mg的流量增加
样品空穴浓度下降
峰强减弱
峰位红移。结果表明:UVL峰是来自于易热分解的浅施主(V
N
H)与浅受主(Mg
Ga
)之间的跃迁
并受到深施主(Mg
Ga
V
N
)与浅受主(Mg
Ga
)自补偿效应的影响。实验上随着PL光谱激发强度的增强
UVL峰位约有260 meV的蓝移
结合超晶格极化场下的能带模型分析
认为这是极化效应导致的锯齿状能带中
V
N
H与Mg
Ga
之间跃迁方式的改变引起的现象。
Investigation on the origin and relative factors of ultraviolet luminescence (UVL) by photoluminescence and Hall measurements for the Mg-doped Al
x
Ga
1-x
N/GaN superlattice with varying annealing temperature and excitation intensity is presented. The intensity of UVL increases to the maximum and then decreases sharply and the peak exhibites a redshift when the annealing temperature increased in the N
2
atmosphere; at the same activating condition
the hole concentration of the sample and the intensity of UVL decreases and the peak shifts to the lower energy as the Mg content increases. The results indicated that the transition between the shallow donors (V
N
H) that is easily disassembled by heat and shallow acceptors (Mg
Ga
) caused UVL
which also competes with the transition between deep donors (Mg
Ga
V
N
) and shallow acceptors (Mg
Ga
) due to the effect of self-compensation by redshift. The blueshift of UVL is about 260 meV with increasing the excitation density. Studying by the model of band structure of superlattice on the effect of polarization
it was suggested that UVL arises from the change of the transition between V
N
H and Mg
Ga
in a sawtooth-like band structure due to polarization effect. According to the early reports
the origin of UVL in Mg-doped GaN is still unclear. In this report
UVL is found in Mg-doped Al
x
Ga
1-x
N/GaN superlattice and the difference from Mg-doped GaN is observed through the photoluminescence due to the strong polarization effect in superlattice. This study will help us to disclose the process of the radiative transition especially caused by defects in superlattice clearly and understand the origin of ultraviolet luminescence in these Mg-doped GaN-based materials further.
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