Bias-temperature life tests for planar-type VPE-grown InGaAs/InP heterostructure APD's

The fabrication processings and the preliminary bias-temperature life tests for planar-type InGaAs/InP heterostructure avalanche photodiodes (HAPD's) made from VPE-grown wafers are presented. The plasma deposited SiN
x
passivation film showed a surface state density N
ss
of less than 10
¹²
cm
^-2
. eV
^-1
. An anomalous behavior of Cd diffusion velocity was observed in the process of the guard-ring formation. A Cr/Au p-side electrode made it possible to reduce the contact failure compared to an Au/Zn contact. Bias-temperature life tests were carried out at three temperature levels: 80, 120, and 180°C. Low-bias life tests (
V_{R} = 10
V) were tried at first for the diodes without a guard-ring structure for times exceeding 10 000 h. The HAPD's with the guard-ring have been tested under the condition of high electric field (
>4 \times 10^{5}
V/cm). The stable devices have been operating up to 6000 h under the high field condition even at 180°C. The HAPD's are still at the prototype stage. Thus, the test results are considered to be encouraging as to achieving highly reliable photodiodes.