High Quality P-Type Mg-Doped β-Ga2O3–δ Films for Solar-Blind Photodetectors

The (
$\overline {{2}} {01}$
)-oriented Mg-doped
$\boldsymbol {\beta }$
-
${\text {Ga}}_{2}{\text {O}}_{3- \delta }$
films were grown on (0001)-sapphire substrates by pulsed laser deposition (PLD) at various oxygen partial pressures (
$\text{P}_{\text {O}}\,\,=10$
-40mTorr). The conductivity type of the as-deposited Mg-doped
${\beta }$
-
${\text {Ga}}_{2}{\text {O}}_{3- \delta }$
films is proved to be
${p}$
-type according to the transfer characteristic curves of a top-gate field effect transistor (FET) and rectification curves of the Mg-doped /undoped
${\beta }$
-
${\text {Ga}}_{2}{\text {O}}_{3- \delta }$
junction. In addition, the two-terminal solar-blind photodetectors based on Mg-doped
${\beta }$
-
${\text {Ga}}_{2}{\text {O}}_{3- \delta }$
films prepared at
$\text{P}_{\text {O}} =30$
mTorr exhibite a good optoelectrical performance with a low dark current of 0.19 pA at 10 V, a high
$\text{I}_{\text {254nm}}/\text{I}_{\text {dark}}$
ratio of
${1.3}\,\,\times \,\,{10}^{{4}}$
, fast rise (
${\tau }_{\text {r1}} =0.035\text{s}$
and
${\tau }_{\text {r2}} =0.241\text{s}$
) and decay (
${\tau }_{\text {d1}} =0.022\text{s}$
and
${\tau }_{\text {d2}} =0.238\text{s}$
) times. The present work indicates that the
${p}$
-type Mg-doped
${\beta }$
-
${\text {Ga}}_{2}{\text {O}}_{3- \delta }$
films can be used in the third-generation ultraviolet photodetectors.