부산대학교 도서관

We investigated 60-nm $\hbox{In}_{0.52}\hbox{Al}_{0.48}\hbox{As}\hbox{/} \break\hbox{In}_{0.53}\hbox{Ga}_{0.47}\hbox{As}$ pseudomorphic high-electron mobility transistors (p-HEMTs) fabricated by using a Ne-based atomic-layer-etching (ALET) technology. The ALET process produced a reproducible etch rate of 1.47 $\hbox{\bf{\AA}}$ /cycle for an InP etch stop layer, an excellent InP etch selectivity of 70 against an $ \hbox{In}_{0.52}\hbox{Al}_{0.48}\hbox{As}$ barrier layer, and an rms surface-roughness value of 1.37 $\hbox{\bf{\AA}}$ for the exposed $\hbox{In}_{0.52}\hbox{Al}_{0.48}\hbox{As}$ barrier after removing the InP etch stop layer. The application of the ALET technology for the gate recess of 60-nm $\hbox{In}_{0.52} \hbox{Al}_{0.48}\hbox{As}\hbox{/}\hbox{In}_{0.53}\hbox{Ga}_{0.47}\hbox{As}$ p-HEMTs produced improved device parameters, including transconductance $(G_{M})$, cutoff frequencies $(f_{T})$, and electron saturation velocity $(\upsilon_{\rm sat})$ in the channel layer, which is mainly due to the high etch selectivity and low plasma-induced damage to the gate area. The 60-nm $\hbox{In}_{0.52}\hbox{Al}_{0.48}\hbox{As}\hbox{/}\hbox{In}_{0.53}\hbox{Ga}_{0.47}\hbox{As}$ p-HEMTs fabricated by using the ALET technology exhibited $G_{M, {\rm Max}} = \hbox{1.17}\ \hbox{S/mm}$ , $f_{T} = \hbox{398}\ \hbox{GHz}$ , and $\upsilon_{\rm sat} = \hbox{2.5}\ \times \hbox{10}^{7}\ \hbox{cm/s}$.