# Investigation of Hydrogen Flux Influence on InGaP Layer and Device Uniformity
## 3 Results and Discussion  
### Influence of Total H\({}_{2}\) Flux on the Uniformity of the InGaP Single Layer  
In our research, we meticulously designed and executed a series of experiments to thoroughly examine the impact of varying H\({}_{2}\) carrier gas fluxes on the electrical uniformity of InGaP epitaxial wafers. Given the critical role of carrier gas flux in determining the quality of epitaxial layer growth during the fabrication of semiconductor materials, understanding its effects is fundamental for material optimization and enhancing device dependability. Our experimental focus was on two primary growth parameters: the growth temperature and the V/III ratio. These parameters are instrumental in influencing the epitaxial layer's crystal structure, uniformity, components, and doping levels. By setting the growth temperature and V/III ratio to 650 \({}^{\circ}\)C and 80, respectively, we aimed to isolate and assess the influence of H\({}_{2}\) carrier gas flux variations on the epitaxial wafer's electrical uniformity within a controlled and stable experimental framework. To thoroughly investigate how varying H\({}_{2}\) carrier gas fluxes affect epitaxial wafer performance, we selected four distinct fluxes for our study: 15,000 sccm, 17,000 sccm, 19,000 sccm, and 21,000 sccm. This range enabled us to observe the impact of H\({}_{2}\) carrier gas flux variations on the uniformity of the epitaxial wafers effectively. Our experimental approach adhered strictly to the standard procedures for epitaxial wafer growth, ensuring uniform growth conditions across all samples. The specific growth parameters for each sample are detailed in Table 1. Sample-a to Sample-d correspond to H\({}_{2}\) carrier gas flow rates of 21,000 sccm to 15,000 sccm, respectively. By evaluating the performance of these samples under identical measurement conditions, we were able to conduct a detailed analysis of how the total H\({}_{2}\) carrier flux influences the electrical uniformity of InGaP epitaxial wafers. The insights gained from this analysis are instrumental in refining the epitaxial growth process and enhancing device performance. Figure 1 presents the sheet resistance measurements for the InGaP epitaxial layers, observed under varying H\({}_{2}\) fluxes. Figure 1a-d corresponds to the sheet resistance test results of Sample-a-Sample-d. As can be seen in Figure 1, Sample-b has the best sheet \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample No.** & **H\({}_{2}\) Flux** & **Growth Temperature** & **V/III** \\ \hline Sample-a & 15,000 sccm & & \\ Sample-b & 17,000 sccm & & \\ Sample-c & 19,000 sccm & & \\ Sample-d & 21,000 sccm & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The impact of total H\({}_{2}\) flux on the properties of epitaxial layers. The H\({}_{2}\) flux, growth temperature, and V/III ratio for each sample are shown. resistance uniformity, at 0.53%. Figure 2 illustrates the influence of H\({}_{2}\) flux on the growth rate, sheet resistance, and uniformity of sheet resistance in InGaP. Figure 2a demonstrates that with an increase in total H\({}_{2}\) flux, there is generally an upward trend in growth rate, except for a notable dip at 19,000 sccm. This decrease is followed by a significant rise as the H\({}_{2}\) flux progresses from 19,000 sccm to 21,000 sccm. The primary cause of this pattern is that a higher H\({}_{2}\) flux enhances the delivery of growth precursors through the chamber, thereby accelerating the growth rate. However, this trend diverges from predictions made by the simple boundary layer model. A plausible explanation for this anomaly is the premature depletion of TMIn during InGaP's epitaxial growth as TMGa and TMIn are introduced. As the total H\({}_{2}\) flux increases, both TMGa and TMIn are expected to rise proportionately, exacerbating TMIn's early depletion and, consequently, impacting the growth rate increase. While the simple boundary layer model does not fully account for the total H\({}_{2}\) flux impact on growth rate, it does shed light on certain trends observed.