Abstract: Main cells that constitute a semiconductor element having a trench gate structure include first cells, and second cells having a structure in which gate insulating films are more easily broken by energization than those in the first cells, and the number of which is smaller than that of the first cells. At a time of driving the semiconductor element, a common gate drive voltage is applied to gate electrodes of the first cells and the second cells. An electrical characteristic is measured to detect failure of the second cells due to energization at the time of driving. The gate electrodes of the failed second cells are electrically isolated from the gate electrodes of the first cells so that the gate drive voltage is not applied to the failed second cells. The failure of the first cells is predicted based on the failure of the second cells.

Abstract: Provided is a ceramic composition capable of achieving a light scattering function while maintaining optical properties at a high level. The ceramic composition comprises a fluorescence phase comprising a fluorescent material and a light-scattering phase comprising a lanthanum oxide. The lanthanum oxide may be, for example, at least one selected from LaAlO3 and La2O3. The ratio of the fluorescent material (or the fluorescence phase) to the lanthanum oxide (or the light-scattering phase), the former/the latter, may be 99.9/0.1 to 50/50 in terms of volume ratio.

Abstract: Provided is a ceramic composition capable of achieving a light scattering function while maintaining optical properties at a high level. The ceramic composition comprises a fluorescence phase comprising a fluorescent material and a light-scattering phase comprising a lanthanum oxide. The lanthanum oxide may be, for example, at least one selected from LaAlO3 and La2O3. The ratio of the fluorescent material (or the fluorescence phase) to the lanthanum oxide (or the light-scattering phase), the former/the latter, may be 99.9/0.1 to 50/50 in terms of volume ratio.