| 摘要 |
<p>Under photoluminescence (PL) excitation, the lateral spreading of photo-excited carriers can suppress the photoluminescence signal from double heterostructure (DH) wafers (12) containing a p-n junction. In any DH with a p-n junction in the active layer, PL is suppressed if the power of the excitation source (16) does not exceed a threshold value. This effect can be advantageously used for a nondestructive optical determination of the top cladding layer sheet conductance as well as p-n junction misplacement, important parameters for injection lasers and LEDs. Photoluminescence is detected by spectrometer (36) while the intensity from optical source (16) is varied by variable attenuator (20). A photoluminescence intensity versus excitation beam intensity characteristic is produced by a recorder (38) responsive to the output of spectrometer (36) and to the output of the variable attenuator (20) as seen by power monitor (26). </p> |
