*Article* **GaAs Nanomembranes in the High Electron Mobility Transistor Technology**

**Dagmar Gregušová \* , Edmund Dobroˇcka, Peter Eliáš , Roman Stoklas, Michal Blaho, Ondrej Pohorelec , Štefan Hašˇcík, Michal Kuˇcera and Róbert Kúdela**

> Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská Cesta 9, 841 04 Bratislava, Slovakia; edmund.dobrocka@savba.sk (E.D.); peter.elias@savba.sk (P.E.); roman.stoklas@savba.sk (R.S.); michal.blaho@savba.sk (M.B.); ondrej.pohorelec@savba.sk (O.P.); stefan.hascik@savba.sk (Š.H.); michal.kucera@savba.sk (M.K.); robert.kudela@savba.sk (R.K.)

**\*** Correspondence: dagmar.gregusova@savba.sk

**Abstract:** A 100 nm MOCVD-grown HEMT AlGaAs/InGaAs/GaAs heterostructure nanomembrane was released from the growth GaAs substrate by ELO using a 300 nm AlAs layer and transferred to sapphire. The heterostructure contained a strained 10 nm 2DEG In0.23Ga0.77As channel with a sheet electron concentration of 3.4 <sup>×</sup> <sup>10</sup><sup>12</sup> cm−<sup>2</sup> and Hall mobility of 4590 cm2<sup>V</sup> −1 s −1 , which was grown close to the center of the heterostructure to suppress a significant bowing of the nanomembrane both during and after separation from the growth substrate. The as-grown heterostructure and transferred nanomembranes were characterized by HRXRD, PL, SEM, and transport measurements using HEMTs. The InGaAs and AlAs layers were laterally strained: ∼ −1.5% and ∼ −0.15%. The HRXRD analysis showed the as-grown heterostructure had very good quality and smooth interfaces, and the nanomembrane had its crystalline structure and quality preserved. The PL measurement showed the nanomembrane peak was shifted by 19 meV towards higher energies with respect to that of the as-grown heterostructure. The HEMTs on the nanomembrane exhibited no degradation of the output characteristics, and the input two-terminal measurement confirmed a slightly decreased leakage current.

**Keywords:** nanomembrane; hybrid integration; GaAs; InGaAs channel; epitaxial lift-off; HEMT; van der Waals
