Impact of strain-induced bow on the performance of VCSELs on 150mm GaAs- and Ge-substrate wafers
Impact of strain-induced bow on the performance of VCSELs on 150mm GaAs- and Ge-substrate wafers
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应变引起的弯曲对 150mm GaAs 和 Ge 衬底晶圆上的 VCSEL 性能的影响
DOI：
10.1117/12.2624492
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Baker J
中科院分区：
文献类型：
--
作者：
Baker J
测量了在GaAs衬底上生长的VCSEL外延结构的应变诱导晶圆弯曲，并与Ge衬底的应变诱导晶圆弯曲进行了比较。我们发现，GaAs晶圆中心和边缘之间约160 μm的高度差会导致显著的温度梯度，从而对外延结构顶部DBR高al层的氧化速率有很大影响。我们测量了砷化镓晶圆由此产生的中心到边缘的氧化长度变化~ 3 μm。我们评估了圆片弯曲和外延层不均匀性以及炉内温度变化的影响，发现弯曲的影响占主导地位。我们采用了一种快速制造（VQF）方法，在150mm GaAs衬底晶圆上快速生产氧化物限制的vcsel，以评估对器件性能的影响。通过测量阈值电流密度在20 ~ 70℃之间，我们发现增益光谱峰与谐振腔波长对准时对应的温度变化为~ 25℃。然而，我们仍然发现零失谐时边缘器件的阈值电流密度较低，我们将其归因于材料变化。我们分离了对器件性能的不同贡献，以隔离材料变化的影响。我们将这种剩余的空间不均匀性与生长在Ge衬底上的VCSELs进行了比较。
The strain-induced wafer bow for VCSEL epitaxial structures grown on GaAs substrates is measured and compared to that of Ge substrates. We find that the ~ 160 μm height difference between the centre and edge of a GaAs wafer results in a significant temperature gradient and hence has a large effect on oxidation rate in the high-Al layer in the top DBR of the epi-structure. We measure a resultant centre-to-edge variation in oxidation length of ~ 3 μm for a GaAs wafer. We assess the contributions of wafer bow and epi-layer non-uniformity, as well as temperature variation in the furnace, and find that the effect of the bow dominates. We employ a Very Quick Fabrication (VQF) method to rapidly produce oxide confined VCSELs across a 150 mm GaAs substrate wafer to assess the impact on device performance. By measuring threshold current density between 20 and 70 ℃, we find ~ 25 ℃ variation in the temperature corresponding to the alignment of the spectral peak of gain with the cavity resonance wavelength. However, we still find that the threshold current density at zero detuning, is lower for edge devices, which we attribute to material variation. We disentangle the different contributions to device performance to isolate the effect of material variation. We compare this remaining spatial non-uniformity to that of VCSELs grown on Ge substrates.