An effect of source/drain spacing in AlGaN/GaN HEMT on linearity to improve device reliability

In this work we analysed the performance of AlGaN/GaN HEMT based on the linearity metrics for variable source/drain spacing with a fixed gate length ($1 \mu\mathrm{m}$) using Sentaurus TCAD device simulator. Various figure of merits such as transconductance, higher order transconductance coefficients (gm1, gm 3), second/third-order voltage intercept point (VIP2/VIP3), third-order input intercept point (IIP3), third order intermodulation distortion (IMD3), and 1-dB compression point have been investigated and reported here. From the primary observation, it is found that the device with the source spacing ($\mathrm{L}_{\text{SG}}=0.25\ \mu\mathrm{m}$) and the drain spacing ($\mathrm{L}_{\text{DG}}=0.75 \mu\mathrm{m}$) for fixed gate length ($\text{Lg}=1\ \mu\mathrm{m}$) shows an improved device linearity as compared to the combination of $\mathrm{L}_{\text{SG}}/ \mathrm{L}_{\text{DG}}=0.5/0.5,\ 0.75/0.25,\ 1/1\ \mu\mathrm{m}$. This study can be used in optimising and designing the HEMT structure for high frequency applications.