Hole tunneling has been studied in single-barrier p-type AlxGa1-xAs capacitors. The current-voltage (I-V) curves with no magnetic field are remarkably complex. At low bias, in the direct tunneling regime, several reproducible voltage-controlled negative resistance (VCNR) regimes occur. VCNR is unchanged for magnetotunneling in magnetic fields B perpendicular to the accumulation layer; the voltages for minima in the derivative of I-V curves for -0.4 V≲VG≲-0.1 V are constant. For -0.8 V≲VG≲-0.4 V, and for B≳9 T, there are minima in the derivative curves whose positions are proportional to magnetic field. The origin of the complex structure for -0.4 V≲VG≲-0.1 V is uncertain but may be connected with conversion of heavy holes to light holes that tunnel through Al0.5Ga0.5As. © 1990.