Compensation in ( 2 ¯ 01 ) homoepitaxial β-Ga2O3 thin films grown by metalorganic vapor-phase epitaxy

Homoepitaxial growth of β-Ga 2O 3 using metalorganic vapor-phase epitaxy (MOVPE) on several different crystal orientations has previously been studied, but growth on the ( 2 ¯ 01 ) plane has remained comparatively unexplored. To investigate this, we grew Si-doped and unintentionally doped (UID) homoepitaxial layers simultaneously on Sn-doped ( 2 ¯ 01 ) and ( 010 ) substrates under conditions optimized for ( 010 ) growth. We report herein on results from current–voltage and capacitance–voltage (IV and CV) and deep level transient spectroscopy (DLTS) characterization of Schottky diodes fabricated on these samples. Devices on ( 010 ) display nearly ideal Schottky diode JV and CV behaviors while for ( 2 ¯ 01 ) evidence of complete depletion of >2 μm thickness, UID epilayers are observed. The ( 2 ¯ 01 ) UID diodes exhibited Mott–Gurney space charge-limited transport and were completely depleted even at zero bias. Doping ( 2 ¯ 01 ) samples heavily with Si was sufficient to overcome background compensation and reproduce near-ideal diode behavior. DLTS data from these doped devices show, in addition to typical negative majority-carrier transients, positive transients with a broad energy distribution, possibly indicating traps on structural defects or surface states. An etch pit analysis under SEM revealed intricate structures of the grown layers. Cross-sectional TEM characterization of a ( 2 ¯ 01 ) sample revealed a high density of structural defects within the epitaxial layer, likely stacking faults. Hypotheses for the origins of the compensation in ( 2 ¯ 01 ) β-Ga 2O 3 homoepitaxial MOVPE growth under ( 010 ) growth conditions are discussed; the most likely explanation is the presence of defect states introduced by the stacking faults visible under TEM.