A semiconductor device comprising: a first semiconductor channel of a second conductivity type which electrically separates a first semiconductor source of a first conductivity type from a first drift region of the first conductivity type, and which is gated by a first gate electrode; a second semiconductor channel of the first conductivity type which electrically separates a second semiconductor source of the second conductivity type from a second drift region of the second conductivity type, and which is gated by a second gate electrode; said first and second semiconductor sources being electrically connected together; a first external terminal, which is electrically connected to said first drift region, and a second external terminal, which is electrically connected to said second drift region; said first gate electrode being operatively connected to receive a potential which is dependent on a potential of said second drift region, and said second gate electrode being operatively connected to receive a potential which is dependent on a potential of said first drift region; whereby said first and second external terminals are configured to provide rectification therebetween, characterized in that said second gate electrode is connected to a first probe contact which is fed by said first drift region via a probe contact region of the second conductivity type, wherein said first probe contact is separate from said first external terminal; and said first gate electrode is connected to a second probe contact which is fed by said second drift region via a probe contact region of the first conductivity type, wherein said second probe contact is separate from said second external terminal. a first semiconductor channel of a second conductivity type which electrically separates a first semiconductor source of a first conductivity type from a first drift region of the first conductivity type, and which is gated by a first gate electrode; a second semiconductor channel of the first conductivity type which electrically separates a second semiconductor source of the second conductivity type from a second drift region of the second conductivity type, and which is gated by a second gate electrode; said first and second semiconductor sources being electrically connected together; a first external terminal, which is electrically connected to said first drift region, and a second external terminal, which is electrically connected to said second drift region; said first gate electrode being operatively connected to receive a potential which is dependent on a potential of said second drift region, and said second gate electrode being operatively connected to receive a potential which is dependent on a potential of said first drift region; whereby said first and second external terminals are configured to provide rectification therebetween, characterized in that said second gate electrode is connected to a first probe contact which is fed by said first drift region via a probe contact region of the second conductivity type, wherein said first probe contact is separate from said first external terminal; and said first gate electrode is connected to a second probe contact which is fed by said second drift region via a probe contact region of the first conductivity type, wherein said second probe contact is separate from said second external terminal.