Reduction of V-pit density and depth in InGaN semibulk templates and improved LED performance with insertion of high temperature semibulk layers
Reduction of V-pit density and depth in InGaN semibulk templates and improved LED performance with insertion of high temperature semibulk layers
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DOI：
10.1088/1361-6641/ac6d01
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发表时间：
2022-05
影响因子：
1.9
通讯作者：
E. L. Routh;M. Abdelhamid;P. Colter;A. J. Bonner;N. El-Masry;S. Bedair
中科院分区：
文献类型：
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作者：
E. L. Routh;M. Abdelhamid;P. Colter;A. J. Bonner;N. El-Masry;S. Bedair
据报道，使用半体（SB）生长方法，具有有效in含量为~ 10%的高度松弛的InGaN模板具有降低的v坑密度和改善的表面粗糙度。这是通过插入五周期高温SB (HTSB) InGaN SB区域实现的。本报告表明，通过在模板中插入HTSB可以获得更高质量的InGaN模板，而不是用超晶格结构结束模板或用GaN中间层填充凹坑。三种SB样品分别在有和没有HTSB层的情况下生长。采用二次离子质谱法、光致发光法和x射线衍射法测定了模板的有效in含量分别为9.6%、5.8%和8.7%。原子力显微镜观察发现，两个HTSB区的表面粗糙度从4.4 nm提高到1.7 nm，平均v坑密度和深度分别从7.6 × 10−7提高到4.5 × 10−7 cm−2和8.2提高到2.8 nm。同时，具有HTSB区域的样品的最大v坑深度从30.5 nm减小到9.6 nm。研究了两个led，一个具有两个HTSB区域，一个仅具有最上面的HTSB区域。具有两个HTSB区域的LED在注入电流峰值时的光功率密度高1.4倍，显示出高1.3倍的外量子效率峰值，并且EQE下垂开始延迟。这些结果表明，采用改进的生长方法可以提高高含量SB模板的质量。
Highly relaxed InGaN templates with an effective In-content of ∼10% that exhibit reduced V-pit density and an improved surface roughness are reported using the semibulk (SB) growth approach. This was achieved by the insertion of five period high temperature SB (HTSB) InGaN SB regions. This report demonstrates that better quality InGaN templates can be achieved by the insertion of HTSB within the templates, rather than by ending the templates with a superlattice structure or by refilling the pits with GaN interlayers. Three SB samples were grown with and without the HTSB layers. Using secondary-ion mass spectrometry, photoluminescence, and x-ray diffraction, the effective In-content of the templates was determined to be 9.6%, 5.8%, and 8.7%. Using atomic force microscopy, the surface roughness was found to improve from 4.4 to 1.7 nm by using the two HTSB regions, and the average V-pit density and depth improved from 7.6 × 10−7 to 4.5 × 10−7 cm−2 and 8.2 to 2.8 nm, respectively. Also, the maximum V-pit depth was reduced from about 30.5 nm to about 9.6 nm in the sample with the HTSB regions. Two LEDs were studied, one with both HTSB regions, and one with only the topmost HTSB. The optical power density of the LED with both HTSB regions was 1.4 times higher at the peak injection current, displayed a ∼1.3 times higher external quantum efficiency peak, and a delay of the EQE droop onset. These results show that higher In-content SB templates can be improved with the implementation of a modified growth approach.